1
Atmospheric Formation of Ultrafine Particles
Charles Stanier Assistant ProfessorUniversity of IowaDepartment of Chemical and
Biochemical Engineeringcstanierengineeringuiowaedu
2
Outline
What is atmospheric new particle formationSome examples
Physical measurementsChemical measurementsModeling
What fraction of particles are from new particle formation vs combustion
3
What is Nucleation
Molecules
Neutral or ion clusters
Ternary or Ion-Induced Nucleation
Detectable Aerosol Particles001-10 cm-3s-1 regional eventsup to 105 cm-3s-1 in plumes
Initial Growth
Further Growth (1-20 nmhr)
CCNAmmoniumSulfateOrganics~ 1 nm 3 nm
LossBy
CondensationTo Pre-existingSurface Area
4
Nucleation Overview
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
NH3
5
Nucleation Observations
Kulmala McMurry et al (2004) J Aerosol Sci 35 pp 143-176
6
Particle Size
nmmicrom
10001
10001
10001
10001 10 100
Ultrafine
Fine Particles (lt 25 microm)
Con
cent
ratio
n Number Distribution
Mass Distribution
7
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
8
0 25 50 75 100
Number vs Mass Distribution
Pittsburgh PA2001-2002
Aerosol Mass (microgm3)
Num
ber
(c
m3 )
10x104
20x104
Negative correlationRelated to nucleation activityOccurring over wide area
9
New Particle Formation vs Visibility
USX Tower
USX Tower
10
Other Aerosol Impacts Visibility amp Climate
EPA (2001) National Air Quality Status and Trends
Yosemite CA
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
11
Physical Measurements
12
Dry-Ambient Aerosol Size Spectrometer
Reconfigured commercial instrumentsRH control systemInlet particle losses characterizationCustom control data acquisition and data reduction software
13
Nucleation Frequency by Month
0
50
100
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
gt 1-hr Duration lt 1-hr Duration None
2001 2002
Frac
tion
of
Day
s W
ith
Nu
clea
tion
Significant fraction of days (30+)Most prevalent in spring fall
Pittsburgh 2001-2002
14
Example No NucleationP
arti
cle
Size
(n
m)
10
100
500
0000Time of Day
0600 1200 1800 2400
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Nu
mbe
r (
cm
3)
12x104
6x104
Pittsburgh August 10 2001
15
Example Weak Nucleation
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Par
ticl
e Si
ze (
nm
)
10
100
500
Nu
mbe
r (
cm
3)
12x104
6x104
0000Time of Day
0600 1200 1800 2400
Pittsburgh July 2 2001
16
Sunlight and New Particle Formation
SUNRISE
Cloudy Morning
0000Time of Day
0600 1200 1800 2400
Cloud Free Morning
Par
ticl
e Si
ze (
nm
)
10
100
500
10
100
500Pittsburgh
Nov 10 2001
PittsburghNov 11 2001
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
2
Outline
What is atmospheric new particle formationSome examples
Physical measurementsChemical measurementsModeling
What fraction of particles are from new particle formation vs combustion
3
What is Nucleation
Molecules
Neutral or ion clusters
Ternary or Ion-Induced Nucleation
Detectable Aerosol Particles001-10 cm-3s-1 regional eventsup to 105 cm-3s-1 in plumes
Initial Growth
Further Growth (1-20 nmhr)
CCNAmmoniumSulfateOrganics~ 1 nm 3 nm
LossBy
CondensationTo Pre-existingSurface Area
4
Nucleation Overview
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
NH3
5
Nucleation Observations
Kulmala McMurry et al (2004) J Aerosol Sci 35 pp 143-176
6
Particle Size
nmmicrom
10001
10001
10001
10001 10 100
Ultrafine
Fine Particles (lt 25 microm)
Con
cent
ratio
n Number Distribution
Mass Distribution
7
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
8
0 25 50 75 100
Number vs Mass Distribution
Pittsburgh PA2001-2002
Aerosol Mass (microgm3)
Num
ber
(c
m3 )
10x104
20x104
Negative correlationRelated to nucleation activityOccurring over wide area
9
New Particle Formation vs Visibility
USX Tower
USX Tower
10
Other Aerosol Impacts Visibility amp Climate
EPA (2001) National Air Quality Status and Trends
Yosemite CA
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
11
Physical Measurements
12
Dry-Ambient Aerosol Size Spectrometer
Reconfigured commercial instrumentsRH control systemInlet particle losses characterizationCustom control data acquisition and data reduction software
13
Nucleation Frequency by Month
0
50
100
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
gt 1-hr Duration lt 1-hr Duration None
2001 2002
Frac
tion
of
Day
s W
ith
Nu
clea
tion
Significant fraction of days (30+)Most prevalent in spring fall
Pittsburgh 2001-2002
14
Example No NucleationP
arti
cle
Size
(n
m)
10
100
500
0000Time of Day
0600 1200 1800 2400
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Nu
mbe
r (
cm
3)
12x104
6x104
Pittsburgh August 10 2001
15
Example Weak Nucleation
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Par
ticl
e Si
ze (
nm
)
10
100
500
Nu
mbe
r (
cm
3)
12x104
6x104
0000Time of Day
0600 1200 1800 2400
Pittsburgh July 2 2001
16
Sunlight and New Particle Formation
SUNRISE
Cloudy Morning
0000Time of Day
0600 1200 1800 2400
Cloud Free Morning
Par
ticl
e Si
ze (
nm
)
10
100
500
10
100
500Pittsburgh
Nov 10 2001
PittsburghNov 11 2001
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
3
What is Nucleation
Molecules
Neutral or ion clusters
Ternary or Ion-Induced Nucleation
Detectable Aerosol Particles001-10 cm-3s-1 regional eventsup to 105 cm-3s-1 in plumes
Initial Growth
Further Growth (1-20 nmhr)
CCNAmmoniumSulfateOrganics~ 1 nm 3 nm
LossBy
CondensationTo Pre-existingSurface Area
4
Nucleation Overview
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
NH3
5
Nucleation Observations
Kulmala McMurry et al (2004) J Aerosol Sci 35 pp 143-176
6
Particle Size
nmmicrom
10001
10001
10001
10001 10 100
Ultrafine
Fine Particles (lt 25 microm)
Con
cent
ratio
n Number Distribution
Mass Distribution
7
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
8
0 25 50 75 100
Number vs Mass Distribution
Pittsburgh PA2001-2002
Aerosol Mass (microgm3)
Num
ber
(c
m3 )
10x104
20x104
Negative correlationRelated to nucleation activityOccurring over wide area
9
New Particle Formation vs Visibility
USX Tower
USX Tower
10
Other Aerosol Impacts Visibility amp Climate
EPA (2001) National Air Quality Status and Trends
Yosemite CA
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
11
Physical Measurements
12
Dry-Ambient Aerosol Size Spectrometer
Reconfigured commercial instrumentsRH control systemInlet particle losses characterizationCustom control data acquisition and data reduction software
13
Nucleation Frequency by Month
0
50
100
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
gt 1-hr Duration lt 1-hr Duration None
2001 2002
Frac
tion
of
Day
s W
ith
Nu
clea
tion
Significant fraction of days (30+)Most prevalent in spring fall
Pittsburgh 2001-2002
14
Example No NucleationP
arti
cle
Size
(n
m)
10
100
500
0000Time of Day
0600 1200 1800 2400
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Nu
mbe
r (
cm
3)
12x104
6x104
Pittsburgh August 10 2001
15
Example Weak Nucleation
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Par
ticl
e Si
ze (
nm
)
10
100
500
Nu
mbe
r (
cm
3)
12x104
6x104
0000Time of Day
0600 1200 1800 2400
Pittsburgh July 2 2001
16
Sunlight and New Particle Formation
SUNRISE
Cloudy Morning
0000Time of Day
0600 1200 1800 2400
Cloud Free Morning
Par
ticl
e Si
ze (
nm
)
10
100
500
10
100
500Pittsburgh
Nov 10 2001
PittsburghNov 11 2001
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
4
Nucleation Overview
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
NH3
5
Nucleation Observations
Kulmala McMurry et al (2004) J Aerosol Sci 35 pp 143-176
6
Particle Size
nmmicrom
10001
10001
10001
10001 10 100
Ultrafine
Fine Particles (lt 25 microm)
Con
cent
ratio
n Number Distribution
Mass Distribution
7
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
8
0 25 50 75 100
Number vs Mass Distribution
Pittsburgh PA2001-2002
Aerosol Mass (microgm3)
Num
ber
(c
m3 )
10x104
20x104
Negative correlationRelated to nucleation activityOccurring over wide area
9
New Particle Formation vs Visibility
USX Tower
USX Tower
10
Other Aerosol Impacts Visibility amp Climate
EPA (2001) National Air Quality Status and Trends
Yosemite CA
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
11
Physical Measurements
12
Dry-Ambient Aerosol Size Spectrometer
Reconfigured commercial instrumentsRH control systemInlet particle losses characterizationCustom control data acquisition and data reduction software
13
Nucleation Frequency by Month
0
50
100
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
gt 1-hr Duration lt 1-hr Duration None
2001 2002
Frac
tion
of
Day
s W
ith
Nu
clea
tion
Significant fraction of days (30+)Most prevalent in spring fall
Pittsburgh 2001-2002
14
Example No NucleationP
arti
cle
Size
(n
m)
10
100
500
0000Time of Day
0600 1200 1800 2400
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Nu
mbe
r (
cm
3)
12x104
6x104
Pittsburgh August 10 2001
15
Example Weak Nucleation
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Par
ticl
e Si
ze (
nm
)
10
100
500
Nu
mbe
r (
cm
3)
12x104
6x104
0000Time of Day
0600 1200 1800 2400
Pittsburgh July 2 2001
16
Sunlight and New Particle Formation
SUNRISE
Cloudy Morning
0000Time of Day
0600 1200 1800 2400
Cloud Free Morning
Par
ticl
e Si
ze (
nm
)
10
100
500
10
100
500Pittsburgh
Nov 10 2001
PittsburghNov 11 2001
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
5
Nucleation Observations
Kulmala McMurry et al (2004) J Aerosol Sci 35 pp 143-176
6
Particle Size
nmmicrom
10001
10001
10001
10001 10 100
Ultrafine
Fine Particles (lt 25 microm)
Con
cent
ratio
n Number Distribution
Mass Distribution
7
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
8
0 25 50 75 100
Number vs Mass Distribution
Pittsburgh PA2001-2002
Aerosol Mass (microgm3)
Num
ber
(c
m3 )
10x104
20x104
Negative correlationRelated to nucleation activityOccurring over wide area
9
New Particle Formation vs Visibility
USX Tower
USX Tower
10
Other Aerosol Impacts Visibility amp Climate
EPA (2001) National Air Quality Status and Trends
Yosemite CA
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
11
Physical Measurements
12
Dry-Ambient Aerosol Size Spectrometer
Reconfigured commercial instrumentsRH control systemInlet particle losses characterizationCustom control data acquisition and data reduction software
13
Nucleation Frequency by Month
0
50
100
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
gt 1-hr Duration lt 1-hr Duration None
2001 2002
Frac
tion
of
Day
s W
ith
Nu
clea
tion
Significant fraction of days (30+)Most prevalent in spring fall
Pittsburgh 2001-2002
14
Example No NucleationP
arti
cle
Size
(n
m)
10
100
500
0000Time of Day
0600 1200 1800 2400
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Nu
mbe
r (
cm
3)
12x104
6x104
Pittsburgh August 10 2001
15
Example Weak Nucleation
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Par
ticl
e Si
ze (
nm
)
10
100
500
Nu
mbe
r (
cm
3)
12x104
6x104
0000Time of Day
0600 1200 1800 2400
Pittsburgh July 2 2001
16
Sunlight and New Particle Formation
SUNRISE
Cloudy Morning
0000Time of Day
0600 1200 1800 2400
Cloud Free Morning
Par
ticl
e Si
ze (
nm
)
10
100
500
10
100
500Pittsburgh
Nov 10 2001
PittsburghNov 11 2001
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
6
Particle Size
nmmicrom
10001
10001
10001
10001 10 100
Ultrafine
Fine Particles (lt 25 microm)
Con
cent
ratio
n Number Distribution
Mass Distribution
7
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
8
0 25 50 75 100
Number vs Mass Distribution
Pittsburgh PA2001-2002
Aerosol Mass (microgm3)
Num
ber
(c
m3 )
10x104
20x104
Negative correlationRelated to nucleation activityOccurring over wide area
9
New Particle Formation vs Visibility
USX Tower
USX Tower
10
Other Aerosol Impacts Visibility amp Climate
EPA (2001) National Air Quality Status and Trends
Yosemite CA
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
11
Physical Measurements
12
Dry-Ambient Aerosol Size Spectrometer
Reconfigured commercial instrumentsRH control systemInlet particle losses characterizationCustom control data acquisition and data reduction software
13
Nucleation Frequency by Month
0
50
100
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
gt 1-hr Duration lt 1-hr Duration None
2001 2002
Frac
tion
of
Day
s W
ith
Nu
clea
tion
Significant fraction of days (30+)Most prevalent in spring fall
Pittsburgh 2001-2002
14
Example No NucleationP
arti
cle
Size
(n
m)
10
100
500
0000Time of Day
0600 1200 1800 2400
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Nu
mbe
r (
cm
3)
12x104
6x104
Pittsburgh August 10 2001
15
Example Weak Nucleation
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Par
ticl
e Si
ze (
nm
)
10
100
500
Nu
mbe
r (
cm
3)
12x104
6x104
0000Time of Day
0600 1200 1800 2400
Pittsburgh July 2 2001
16
Sunlight and New Particle Formation
SUNRISE
Cloudy Morning
0000Time of Day
0600 1200 1800 2400
Cloud Free Morning
Par
ticl
e Si
ze (
nm
)
10
100
500
10
100
500Pittsburgh
Nov 10 2001
PittsburghNov 11 2001
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
7
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
8
0 25 50 75 100
Number vs Mass Distribution
Pittsburgh PA2001-2002
Aerosol Mass (microgm3)
Num
ber
(c
m3 )
10x104
20x104
Negative correlationRelated to nucleation activityOccurring over wide area
9
New Particle Formation vs Visibility
USX Tower
USX Tower
10
Other Aerosol Impacts Visibility amp Climate
EPA (2001) National Air Quality Status and Trends
Yosemite CA
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
11
Physical Measurements
12
Dry-Ambient Aerosol Size Spectrometer
Reconfigured commercial instrumentsRH control systemInlet particle losses characterizationCustom control data acquisition and data reduction software
13
Nucleation Frequency by Month
0
50
100
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
gt 1-hr Duration lt 1-hr Duration None
2001 2002
Frac
tion
of
Day
s W
ith
Nu
clea
tion
Significant fraction of days (30+)Most prevalent in spring fall
Pittsburgh 2001-2002
14
Example No NucleationP
arti
cle
Size
(n
m)
10
100
500
0000Time of Day
0600 1200 1800 2400
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Nu
mbe
r (
cm
3)
12x104
6x104
Pittsburgh August 10 2001
15
Example Weak Nucleation
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Par
ticl
e Si
ze (
nm
)
10
100
500
Nu
mbe
r (
cm
3)
12x104
6x104
0000Time of Day
0600 1200 1800 2400
Pittsburgh July 2 2001
16
Sunlight and New Particle Formation
SUNRISE
Cloudy Morning
0000Time of Day
0600 1200 1800 2400
Cloud Free Morning
Par
ticl
e Si
ze (
nm
)
10
100
500
10
100
500Pittsburgh
Nov 10 2001
PittsburghNov 11 2001
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
8
0 25 50 75 100
Number vs Mass Distribution
Pittsburgh PA2001-2002
Aerosol Mass (microgm3)
Num
ber
(c
m3 )
10x104
20x104
Negative correlationRelated to nucleation activityOccurring over wide area
9
New Particle Formation vs Visibility
USX Tower
USX Tower
10
Other Aerosol Impacts Visibility amp Climate
EPA (2001) National Air Quality Status and Trends
Yosemite CA
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
11
Physical Measurements
12
Dry-Ambient Aerosol Size Spectrometer
Reconfigured commercial instrumentsRH control systemInlet particle losses characterizationCustom control data acquisition and data reduction software
13
Nucleation Frequency by Month
0
50
100
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
gt 1-hr Duration lt 1-hr Duration None
2001 2002
Frac
tion
of
Day
s W
ith
Nu
clea
tion
Significant fraction of days (30+)Most prevalent in spring fall
Pittsburgh 2001-2002
14
Example No NucleationP
arti
cle
Size
(n
m)
10
100
500
0000Time of Day
0600 1200 1800 2400
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Nu
mbe
r (
cm
3)
12x104
6x104
Pittsburgh August 10 2001
15
Example Weak Nucleation
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Par
ticl
e Si
ze (
nm
)
10
100
500
Nu
mbe
r (
cm
3)
12x104
6x104
0000Time of Day
0600 1200 1800 2400
Pittsburgh July 2 2001
16
Sunlight and New Particle Formation
SUNRISE
Cloudy Morning
0000Time of Day
0600 1200 1800 2400
Cloud Free Morning
Par
ticl
e Si
ze (
nm
)
10
100
500
10
100
500Pittsburgh
Nov 10 2001
PittsburghNov 11 2001
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
9
New Particle Formation vs Visibility
USX Tower
USX Tower
10
Other Aerosol Impacts Visibility amp Climate
EPA (2001) National Air Quality Status and Trends
Yosemite CA
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
11
Physical Measurements
12
Dry-Ambient Aerosol Size Spectrometer
Reconfigured commercial instrumentsRH control systemInlet particle losses characterizationCustom control data acquisition and data reduction software
13
Nucleation Frequency by Month
0
50
100
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
gt 1-hr Duration lt 1-hr Duration None
2001 2002
Frac
tion
of
Day
s W
ith
Nu
clea
tion
Significant fraction of days (30+)Most prevalent in spring fall
Pittsburgh 2001-2002
14
Example No NucleationP
arti
cle
Size
(n
m)
10
100
500
0000Time of Day
0600 1200 1800 2400
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Nu
mbe
r (
cm
3)
12x104
6x104
Pittsburgh August 10 2001
15
Example Weak Nucleation
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Par
ticl
e Si
ze (
nm
)
10
100
500
Nu
mbe
r (
cm
3)
12x104
6x104
0000Time of Day
0600 1200 1800 2400
Pittsburgh July 2 2001
16
Sunlight and New Particle Formation
SUNRISE
Cloudy Morning
0000Time of Day
0600 1200 1800 2400
Cloud Free Morning
Par
ticl
e Si
ze (
nm
)
10
100
500
10
100
500Pittsburgh
Nov 10 2001
PittsburghNov 11 2001
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
10
Other Aerosol Impacts Visibility amp Climate
EPA (2001) National Air Quality Status and Trends
Yosemite CA
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
CloudFormation
CloudParticles
ScatteredRadiation
ScatteredRadiation
Earth
Sun
11
Physical Measurements
12
Dry-Ambient Aerosol Size Spectrometer
Reconfigured commercial instrumentsRH control systemInlet particle losses characterizationCustom control data acquisition and data reduction software
13
Nucleation Frequency by Month
0
50
100
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
gt 1-hr Duration lt 1-hr Duration None
2001 2002
Frac
tion
of
Day
s W
ith
Nu
clea
tion
Significant fraction of days (30+)Most prevalent in spring fall
Pittsburgh 2001-2002
14
Example No NucleationP
arti
cle
Size
(n
m)
10
100
500
0000Time of Day
0600 1200 1800 2400
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Nu
mbe
r (
cm
3)
12x104
6x104
Pittsburgh August 10 2001
15
Example Weak Nucleation
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Par
ticl
e Si
ze (
nm
)
10
100
500
Nu
mbe
r (
cm
3)
12x104
6x104
0000Time of Day
0600 1200 1800 2400
Pittsburgh July 2 2001
16
Sunlight and New Particle Formation
SUNRISE
Cloudy Morning
0000Time of Day
0600 1200 1800 2400
Cloud Free Morning
Par
ticl
e Si
ze (
nm
)
10
100
500
10
100
500Pittsburgh
Nov 10 2001
PittsburghNov 11 2001
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
11
Physical Measurements
12
Dry-Ambient Aerosol Size Spectrometer
Reconfigured commercial instrumentsRH control systemInlet particle losses characterizationCustom control data acquisition and data reduction software
13
Nucleation Frequency by Month
0
50
100
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
gt 1-hr Duration lt 1-hr Duration None
2001 2002
Frac
tion
of
Day
s W
ith
Nu
clea
tion
Significant fraction of days (30+)Most prevalent in spring fall
Pittsburgh 2001-2002
14
Example No NucleationP
arti
cle
Size
(n
m)
10
100
500
0000Time of Day
0600 1200 1800 2400
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Nu
mbe
r (
cm
3)
12x104
6x104
Pittsburgh August 10 2001
15
Example Weak Nucleation
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Par
ticl
e Si
ze (
nm
)
10
100
500
Nu
mbe
r (
cm
3)
12x104
6x104
0000Time of Day
0600 1200 1800 2400
Pittsburgh July 2 2001
16
Sunlight and New Particle Formation
SUNRISE
Cloudy Morning
0000Time of Day
0600 1200 1800 2400
Cloud Free Morning
Par
ticl
e Si
ze (
nm
)
10
100
500
10
100
500Pittsburgh
Nov 10 2001
PittsburghNov 11 2001
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
12
Dry-Ambient Aerosol Size Spectrometer
Reconfigured commercial instrumentsRH control systemInlet particle losses characterizationCustom control data acquisition and data reduction software
13
Nucleation Frequency by Month
0
50
100
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
gt 1-hr Duration lt 1-hr Duration None
2001 2002
Frac
tion
of
Day
s W
ith
Nu
clea
tion
Significant fraction of days (30+)Most prevalent in spring fall
Pittsburgh 2001-2002
14
Example No NucleationP
arti
cle
Size
(n
m)
10
100
500
0000Time of Day
0600 1200 1800 2400
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Nu
mbe
r (
cm
3)
12x104
6x104
Pittsburgh August 10 2001
15
Example Weak Nucleation
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Par
ticl
e Si
ze (
nm
)
10
100
500
Nu
mbe
r (
cm
3)
12x104
6x104
0000Time of Day
0600 1200 1800 2400
Pittsburgh July 2 2001
16
Sunlight and New Particle Formation
SUNRISE
Cloudy Morning
0000Time of Day
0600 1200 1800 2400
Cloud Free Morning
Par
ticl
e Si
ze (
nm
)
10
100
500
10
100
500Pittsburgh
Nov 10 2001
PittsburghNov 11 2001
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
13
Nucleation Frequency by Month
0
50
100
Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
gt 1-hr Duration lt 1-hr Duration None
2001 2002
Frac
tion
of
Day
s W
ith
Nu
clea
tion
Significant fraction of days (30+)Most prevalent in spring fall
Pittsburgh 2001-2002
14
Example No NucleationP
arti
cle
Size
(n
m)
10
100
500
0000Time of Day
0600 1200 1800 2400
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Nu
mbe
r (
cm
3)
12x104
6x104
Pittsburgh August 10 2001
15
Example Weak Nucleation
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Par
ticl
e Si
ze (
nm
)
10
100
500
Nu
mbe
r (
cm
3)
12x104
6x104
0000Time of Day
0600 1200 1800 2400
Pittsburgh July 2 2001
16
Sunlight and New Particle Formation
SUNRISE
Cloudy Morning
0000Time of Day
0600 1200 1800 2400
Cloud Free Morning
Par
ticl
e Si
ze (
nm
)
10
100
500
10
100
500Pittsburgh
Nov 10 2001
PittsburghNov 11 2001
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
14
Example No NucleationP
arti
cle
Size
(n
m)
10
100
500
0000Time of Day
0600 1200 1800 2400
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Nu
mbe
r (
cm
3)
12x104
6x104
Pittsburgh August 10 2001
15
Example Weak Nucleation
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Par
ticl
e Si
ze (
nm
)
10
100
500
Nu
mbe
r (
cm
3)
12x104
6x104
0000Time of Day
0600 1200 1800 2400
Pittsburgh July 2 2001
16
Sunlight and New Particle Formation
SUNRISE
Cloudy Morning
0000Time of Day
0600 1200 1800 2400
Cloud Free Morning
Par
ticl
e Si
ze (
nm
)
10
100
500
10
100
500Pittsburgh
Nov 10 2001
PittsburghNov 11 2001
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
15
Example Weak Nucleation
105
104
103
102
Res
pon
sedN
dlo
gDp
(cm
-3)
Par
ticl
e Si
ze (
nm
)
10
100
500
Nu
mbe
r (
cm
3)
12x104
6x104
0000Time of Day
0600 1200 1800 2400
Pittsburgh July 2 2001
16
Sunlight and New Particle Formation
SUNRISE
Cloudy Morning
0000Time of Day
0600 1200 1800 2400
Cloud Free Morning
Par
ticl
e Si
ze (
nm
)
10
100
500
10
100
500Pittsburgh
Nov 10 2001
PittsburghNov 11 2001
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
16
Sunlight and New Particle Formation
SUNRISE
Cloudy Morning
0000Time of Day
0600 1200 1800 2400
Cloud Free Morning
Par
ticl
e Si
ze (
nm
)
10
100
500
10
100
500Pittsburgh
Nov 10 2001
PittsburghNov 11 2001
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
17
Nucleationrsquos Spatial Coverage
Method simultaneous sampling
WindPittsburgh Philadelphia
RuralSampler
Main (Urban)Sampler
PhiladelphiaSampler
38 km 400 km
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
18
Spatial Coverage ResultP
arti
cle
Size
(n
m)
10
100
200
10
100200
38 km apartFebruary 25 2002
Pittsburgh
38 km Upwind Rural Location
400 km apartJuly 2 2001
Pittsburgh
Philadelphia
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
19
Diurnal Pattern
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
0
20000
40000
60000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
3-50
0 nm
Par
ticle
Cou
nt (c
m-3
)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
Non-nucleation w orkdays Non-nucleation w eekends
Regional nucleation days
(b)
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
20
Chemical Measurements
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
21
Aerosol Mass Spectrometer
Zhang Q Jimenez JL Caragaratna M Worsnop D
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
22
Aerosol Mass Spectrometer
Particle Inlet (1 atm)
Jayne et al Aerosol Science and Technology 331-2(49-70) 2000Jimenez et al Journal of Geophysical Research in press 2002
QuadrupoleMass Spectrometer
Thermal Vaporization
ampElectron Impact
Ionization
Aerodynamic Lens
(2 Torr)
Chopper
Turbo Pump
Turbo Pump
Turbo Pump
Time of Flight Region
Particle BeamGeneration
Aerodynamic Sizing Particle Composition
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
23
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
24
September 12 2002 Nucleation EventP
arti
cle
Size
(n
m)
10
100
500
0000 0600 1200 1800 2400
50
0
100
Mas
s Fr
acti
on1
0-6
0 n
m
Nitrate
Ammonium
SulfateOrganics
Mass Fraction (10-60 nm Particles) Aerosol Mass Spectrometer
Zhang amp Jimenez (Univ Colorado-Boulder)
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
25
Chemistry of Growth Particle Mass Spectra at 20-33 nm
Detection of Nucleationby Particle Sizer
Zhang et al Insights into the Chemistry of Nucleation Bursts and New Particle Growth Events in Pittsburgh based on Aerosol Mass Spectrometry Environ Sci Technol in press
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
26
Modeling
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
27
Chemistry of Nucleation Simulation1
SO2(g) + OH + H2O rarrHO2 + H2SO4nH2O
SO2
Inputs Processes Modeled OutputPreexisting Aerosol Distribution
SO2 ConcentrationNH3 ConcentrationUV Light IntensityTemperature amp RH
NH3
SO2 Oxidation to H2SO4H2SO4-H2O-NH3 Nucleation
H2SO4 CondensationParticle Coagulation
Predicted Aerosol Distribution
1Model adapted from Capaldo Kasibhatla Pandis J Geophys Res 1999
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
28
Modeling H2SO4 Nucleation
Photochemical box model
Modeled gas-phase speciesSO2 H2SO4 OH NH3SO2 measured OH and NH3 calculated from measurements
220 fixed size sections ranging in size from 08 nm to 10 microm
T RH SO2 and UV radiation from measurements
Initial distribution available from dry size distributions
Maximum OH concentration assumed for each month scaled based onUV
5 x 106 moleculescm3 in summer1
1 x 106 moleculescm3 in winter2
1Ren et al (2003)2Heard et al (2001)
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
29
Comparison on July 27 2001
Model predicted presence or lack of nucleation on all 19 daysTiming of onset of nucleation within one hour of observations for all 13 eventsSize and shape of growth curve consistent with observationsHigh number concentrations predicted
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
30
Comparison on January 28 2002
25 out of 29 days predicted correctlyTiming of onset of nucleation not as good (6 of 12 within one hour)Growth generally underpredictedwith two exceptionsHigh number concentrations predicted
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
31
Sensitivities
NPF is thought to be sensitive toPM25 darr NPF uarrAmmonia uarr NPF uarr (but not sure how strong this effect)SO2 darr NPF darr (if NH3 in excess hellip that covers
most locations)SO2 darr NPF uarr (if NH3 limited eg northeast US
in summer)Reactive VOCs darrNPF ndash but growth of particles will be
limited ndash so they will not last aslong in the atmosphere
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
32
What fraction of ultrafines are from NPF
To a large extent we do not knowWill vary by locationNPF most important at midday and afternoons
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Threshold chemistrystill Unclear (SO2 + )and will vary from place to pla
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
33
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
Heavy TrafficUrban
AfternoonDownwindSuburbs
Rura
l US
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
34
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
C C a t c e Cou t (b ue) s S S a t c e Cou t ( ed)Pa
rtic
le S
ize
(nm
)
Res
pons
edN
dlo
gDp
(cm
-3)
Bondville Illinois 2005
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
35
Mexico City Mar 17 2006
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
36
Pittsburgh PA
NOV 1
NOV 2
NOV 3
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
37
Pittsburgh PA
NOV 1
NOV 2
NOV 3
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
38
DOWNY DEC 2000 RIVERSIDE MAY 2001
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
39
DOWNY DEC 2000 RIVERSIDE MAY 2001
Traffic
Smog
and
Reg
iona
l Haz
e NPF LessImportant
NPF MoreImportant
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
40
Future Work
In the process of summarizing comparisons between Pittsburgh Rochester New York City Atlanta LA and St LouisUnify measurements detailed modeling and a ldquoscreeningrdquo model that attributes ultrafines to traffic vs new particle formationSort out some details of chemistry and meteorologyMonitor how implementation of further sulfur reductions from power plants and advanced diesel influence new particle formation
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
41
Acknowledgements
StudentsAlicia Kalafut ndash Ultrafine Particle SamplingKazeem Olanrewaju ndash Ultrafine Particle Modeling
University of Iowa CallaboratorsGreg Carmichael Jerry Schnoor Bill Eichinger
Carnegie Mellon CollaboratorsSpyros Pandis Tim Gaydos Andrey Khlystov
Outside CollaboratorsAllen Williams
Illinois Soil and Water SurveyPeter McMurry
University of MinnesotaJimenez Group University of Colorado-Boulder
Jose-Luis Jimenez amp Qi Zhang
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
42
Additional Material
Modeling FrameworkFuture WorkMeasurement TechniqueTraffic and ModelingBondvilleMexicoBackground on PM
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
43
Modeling framework
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
44
Modeling H2SO4 Nucleation
Photochemical box modelModeled gas-phase species
SO2 H2SO4 OH NH3
SO2 measured OH and NH3 calculated from measurements
220 fixed size sectoins ranging in size from 08 nm to 10 microm
( ) ( )( ) ( )
4242
42
42
42
3
2
SOHdepSOHSOH
cond
SOHnucgasSOH
CRRHCR
RHTNHCRnPTOHSORt
C
minus+
+=part
part
( )( ) ( ) ( )idepSOH
Ncondjcoag
SOHnuci
NRRHCRRHNR
RHTNHCRt
N
i minus++
=partpart
42
42 3
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
45
Sulfuric Acid Nucleation Formation
SO2 + OH + M rarr HOSO2 + MHOSO2 + O2 rarr HO2 + SO3(g)
SO3(g) + H2O + M rarr H2SO4(g) + MH2SO4(g) + nH2O(g) rarr H2SO4nH2O(aq)
________________________________________________________________________________________
SO2(g) + OH + O2 + (n+1)H2O rarr HO2 + H2SO4nH2O(aq)
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
46
Chemistry and deposition
Sulfuric acid is produced from the reaction of SO2 and OH1
Deposition
vdep for aerosol dependent on particle size2 10 cms used for H2SO4
3
]][[ 22OHSOkR SOgas =
1kSO2 from DeMore et al (1994)
Hcv
R iidrydep
=
3Brook et al (1999)2Hummelshoj et al (1992)
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
47
Condensation
Condensation rate
Change in number concentration
Flux between fixed sections
)()(2 0ppAKnFDDNJ pi minus= π
42421 SOHiiSOHiiNcond CNFCNFR i minus= minus
( ) ( )[ ]33142
6ip
ip
pimtSOH
iDDRT
DKMF
minus=
+ρπ
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
48
Coagulation
Coagulation rate
Generalized coagulation coefficient
Linear interpolation to preserve mass number
221
1
1 geminus= sumsum
infin
=minus
=minus kNKNNNKfR
jjjkkjkj
k
jjkjkcoag
( )( )βπ 212112 2 DDDDK pp ++=
kk
pkk VV
VVf
minus
minus=
+
+
1
1
kk
kpk VV
VVf
minus
minus=
++
11
β calculated using method of Fuchs (1964)
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
49
Ternary nucleation correlation
Parameterization from Napari et al (2002)Calculates nucleation rate using parameters of T RH NH3 H2SO4
Approximation for initial nuclei size dependent on nucleation rate and T1 nm under typical July conditions08 nm under typical January conditions
Approximation for composition of initial nuclei also dependent on nucleation rate and T
Approximately 4 molecules of sulfuric acid 4 of ammonium in July2 molecules of sulfuric acid 2 of ammonium in January
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
50
Nucleation rates
Presence of gas-phase ammonia necessary for nucleation in July
10 ppt generally enough
Both ammonia and sulfuric acid play important role in January
Cloud cover weaker UV radiation limit production of sulfuric acid
1 2 3 401
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
001 01 101
1
10
100
Sulfuric acid concentration (ppt)
Am
mon
ia (p
pt)
July
January
10-5 10-3 10-1
101 103 105 106
10-5 10-3
10-1
101 103
105 106
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
51
Sensitivity to SO2 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in SO2 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
nChange in SO2 Concentration ()
January
o
f mod
eled
day
s
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
52
Sensitivity to NH3 Emissions
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 1000
2
4
6
8
10
12
14
16
18
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
July
o
f mod
eled
day
s
0102030405060708090100
-100-80 -60 -40 -20 0 20 40 60 80 10002468
10121416182022242628
Day
s w
ith n
ucle
atio
n
Change in NH3 Concentration ()
January
o
f mod
eled
day
s
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
53
Future Work
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
54
Observational Analysis
Determine spatial extent of nucleation from ldquoSupersiterdquo 2001 observations and compare to SO2and NH3 maps
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
55
Observation-Model Hybrid
Prepare model-based predictions of seasonal nucleation frequency timing and growth rateCompare to previous (or new) measurements
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
56
Vertical Profile Sampling
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
57
Vertical Mixing Models
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
58
Perturbed Real Air Samples
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
59
Measurement technique
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
60R
H
APSAPS
Dry sheath airfor Nafion dryers
Vent excessdry air1 LPM
RH
RH
LL -- DM
AD
MA
NN-- D
MA
DM
A
RH
HEPA MFHEPA
HEPA
RH
HEPAMFHEPA
HEPA
AmbientAir In
Dry AirExhaust
CPCCPC
CPCCPC
AmbientAir In
AerosolInlets
MF
Clean Dry ampRegulated Air
3-Way Plug Valvew Solenoid Actuator∆P Flowmeter
Ball Valve Air Actuated
Mass Flow Meter
Bipolar Charger
Nafion DryerRotameter
DryDry--Ambient Aerosol Size SpectrometerAmbient Aerosol Size Spectrometer
Add RH controlled inlets (aerosol water measurement)Control amp data acquisition hardware and software Data processing software to make 6 instruments behave like 1Extensive calibrationSynthesis with other instruments and web-based data visualization
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
61
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
62
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
63
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
64
Scanning Mobility Particle Sizer
Condensation Particle
Counter (CPC)
Sheath Flow
AerosolIn Charger
-
-
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
65
Traffic and modeling
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
66
Traffic Emission Sampling
1E+03
1E+04
1E+05
1E+06
1E+07
0001 001 01 1
Mobility Diameter (microm)
dNd
log(
Dp)
Dilu
tion
Cor
rect
ed (
cm-3
)
0E+00
1E+06
2E+06
3E+06
4E+06
0001 001 01 1
Log Scale Linear Scale
90th
Percentile
10th
Percentile
Note 10th and 90th percentiles on 30-min average size distributions
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
67
Total Emission Factors for Vehicles
0
1E+16
2E+16
3E+16
gt 95 CarsLow Speed
gt 95 CarsHigh Speed
lt 90 CarsHigh Speed
k
g fu
el
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
68
ldquoSpin-Offrdquo of Modeling Techniques
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
69
Calculation of gas-phase ammonia
Estimated from comparison of measured total NH3with PM25 SO4 NO3
When sufficient ammonia is available to neutralize these species excess ammonia assumed to be in gas-phaseOtherwise lower limit for parameterization used
Compared to equilibrium calculations using GFEMN for total NH3 NO3 and SO4
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
70
Bondville
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
71
0
10000
20000
30000
40000
50000
000 600 1200 1800 000
cc
-1
1
3
000 600 1200 1800 000
SO2 Concentration (ppb)
September 18 2005CPC Particle Count (blue) vs SMPS Particle Count (red)
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
72
Nucleation Box Model with May 2003 SWS Data
Constant NH3 of 15 microg m-3 (2200 ppt)Constant SO2 of 4 microg m-3 (154 ppb)Actual median RH and T from May datasetBright sun used for UV OH calculation
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
73
0 3 6 9 12 15 18 21 24
10
100
500
May Base Case
25
3
35
4
45
Part
icle
Siz
e (n
m)
Res
pons
edN
dlo
gDp
(cm
-3)
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
74
Mexico
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
75
PM Background Info
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals
76
Typical Chemical Makeup
InorganicSaltsSO4
2-
NO3-
NH4+
Na+
Cl-
OrganicCompounds
Black Carbon
Metals