romans nitrogen source sensitivity analysis
DESCRIPTION
ROMANS Nitrogen Source Sensitivity Analysis. Mike Barna 1 Marco Rodriguez 2 Kristi Gebhart 1 Bill Malm 1 Bret Schichtel 1 Jenny Hand 2 1 ARD-NPS, Fort Collins, CO 2 CIRA, Fort Collins, CO WRAP Workshop on Regional Emissions & Air Quality Modeling Denver, CO 29-30 July 2008. - PowerPoint PPT PresentationTRANSCRIPT
ROMANS Nitrogen Source Sensitivity Analysis
Mike Barna1
Marco Rodriguez2
Kristi Gebhart1
Bill Malm1
Bret Schichtel1
Jenny Hand2
1 ARD-NPS, Fort Collins, CO2 CIRA, Fort Collins, CO
WRAP Workshop on Regional Emissions & Air Quality ModelingDenver, CO29-30 July 2008
National Park ServiceU.S. Department of the Interior Cooperative Institute
for Research in the Atmosphere
2
• N deposition increasing in the Rocky Mountains
• Alpine ecosystems are susceptible to extra N– N acts as a fertilizer →
ecosystem change– changes may be hard to
reverse– most deposition occurs as
wet dep (~2/3)
• critical load: 1.5 kg/ha/yr
Nitrogen deposition at RMNP
3
• Complex (small scale) diurnal and seasonal mountain circulation patterns.
• Vertical de-coupling due to inversions and stagnation in valleys.
• Orographic precipitation & isolated convective storms
• Lack of observations in remote mountainous areas.
• We still want accurate modeled winds, moisture, temperature, precip for CAMx, trajectories.
Rocky Mountains = magnificent views, fragile ecosystem, complex met
4
• Two field campaigns conducted during spring (April) and summer (July – Aug) of 2006
• Measure concentration and wet dep of important N and S species: NH4, NO3, NH3, NOx, SO4
ROMANS: Rocky Mountain Atmospheric Nitrogen & Sulfur Study
5
Where is the nitrogen coming from?
National Park ServiceU.S. Department of the Interior
Cooperative Institute for Research in the Atmosphere
• local v. regional v. distant?
• oxidized or reduced?
6
Modeling & data analysis ROMANS
• Back trajectories
• Airmass conditional probability
• Dry deposition of ‘missing’ nitrogen
• Tracer simulations -> EOF analysis (Bill Malm)
• ‘Lagrangian process analysis’
• Base case simulation
• Source apportionment of N and S with PSAT
• ‘Hybrid modeling’ (Bret Schichtel)
….at the end, need to reconcile results from these different analyses
7
Domain 136 Km
165 x 129
Domain 212 Km
103 x 115
Domain 34 Km
163 x 118
35 layers – 34 from WRAP, plus a 10-m layer
Applying CAMx in ROMANS
• 36/12/4 km domains
• Met from obs-nudged MM5
• Emissions based on updated 2002 WRAP inventory
8
Distribution of NH3, NO3NH3:•Rapidly dry deposits•Emissions very uncertain•Strong spatial gradients
NO3:•Longer lifetime•Particle or gas phase
9
NH4+
NO3
SO4=
NH3
HNO3
SO2
Beaver Meadows (RMNP) Grant, Nebraska
April 2006 ROMANS base case
10
Rocky Mountain National Park Beginning Apr. 23, 2006 hr 11 (jd 113)Started During Next 1 Hrs, 5 Day Length
‘Lagrangian process analysis’
NH3 Non-transport processes
-8.00
-6.00
-4.00
-2.00
0.00
2.00
4.00
6.00
8.00
10.00
HR0 HR24 HR48 HR72 HR96 HR120
(pp
b)
NH3-Emissions
NH3-Wet deposition
NH3-dry deposition
NH3-inorganic aerosol chemistry
NH3-gas phase chemistry
PNH4 Non-transport processes
-0.20
-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
HR0 HR24 HR48 HR72 HR96 HR120
(ug
/m3)
Emissions
Wet deposition
dry deposition
inorganic aerosol chemistry
gas phase chemistry
What processes influence the concentration within an airmass during its trajectory to RMNP?
•Wet and dry deposition•Emissions•Gas and aerosol chemistry
NH3
NH4+
11
– Sulfur species
• SO2i Primary SO2 emissions
• PS4i Particulate sulfate ion from primary emissions plus secondarily formed sulfate
– Nitrogen species
• RGNi Reactive gaseous nitrogen including primary NOx (NO + NO2) emissions plus nitrate radical (NO3), nitrous acid (HONO) and dinitrogen pentoxide (N2O5).
• TPNi Gaseous peroxyl acetyl nitrate (PAN) plus peroxy nitric acid (PNA)
• NTRi Organic nitrates (RNO3)
• HN3i Gaseous nitric acid (HNO3)
• PN3i Particulate nitrate ion from primary emissions plus secondarily formed nitrate
– Ammonia/ammonium
• NH3i Gaseous ammonia (NH3)
• PN4i Particulate ammonium (NH4)
CAMx PSAT source apportionment
12
CAMx tracer simulations
• ~100 source regions
• Tracers for NH3, NOx, SO2
• Conserved, dry dep, wet dep, total dep
• Use with EOF’s
13
‘Missing nitrogen’ at RMNP
• N dry deposition at RMNP based on CASTNet
• Only three N species are typically ‘measured’ for dry deposition: NH4+, NO3- and HNO3
• What happens when we consider the dry deposition of total N at RMNP?
• Oxidized N (the NOy budget):
• NOx, HNO3, NO3-, PAN + other organic nitrates, HONO, nitrate radical + N2O5
• Reduced N:
• NH3, NH4+
• Simulate this ‘missing N’ with CAMx
14
Annual average modeled nitrogen concentration from CAMx for 2002
CASTNet species:
example ‘missing N’ species:
15
What happens to emitted NOx & NH3
• NH3: rapid deposition, NH3 NH4+, no gas-phase oxidation
• NOx: complicated photochemistry, HNO3 NO3-, some species rapidly deposit (HNO3, NO.)
NH3 NOx
16
CAMx total N vs CASTNet N at RMNP
0.000
0.050
0.100
0.150
0.200
0.250
0.300
0.350
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
2002
ug
-N/m
3pred total red N [ug/m3] ob total red N [ug/m3]
0.000
0.050
0.100
0.150
0.200
0.250
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
2002
kg
-N/h
a
pred total ox N DDep [kg/ha] ob total ox N DDep [kg/ha]
0.000
0.500
1.000
1.500
2.000
2.500
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
2002
ug
-N/m
3
pred total ox N [ug/m3] ob total ox N [ug/m3]
0.000
0.010
0.020
0.030
0.040
0.050
0.060
0.070
0.080
0.090
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
2002
kg
-N/h
a
pred total red N DDep [kg/ha] ob total red N DDep [kg/ha]
Total Reduced N (NH3 + NH4+): Total Oxidized N (NOy):
Conc:
DryDep:
17
Modeled dry deposition at RMNP
0.00
0.05
0.10
0.15
0.20
0.25
0.30
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2002
Nit
rog
en
Dry
De
po
sit
ion
[k
g/h
a]
N-PNO3
N-PNH4
N-NOx
N-PAN
N-NxOy
N-Org N
N-NH3
N-HONO
N-HNO3
18
Modeled dry deposition at RMNP
N-NOx4%
N-PAN3%
N-NxOy10%
N-Org N2%
N-NH328%
N-HONO0%
N-PNO30%
N-HNO353%
N-PNH40%
19
CASTNet v. CAMx dry dep velocities
CASTNet[cm/s]
CAMx[cm/s] Reference Values
HNO3 1.8 6.2 7.51 (conifer forest)3-62
1-53
NH3 N/A 7.5 0.6-3 (low vegetation)4
2-20 (high vegetation)4
NO2 N/A 0.11 0.13
0.1-0.55
OrgN N/A 0.18
NxOy N/A 5.6
PAN N/A 0.08
PM 0.20 0.03 <0.53
0.1 – 0.52
0.01 – 0.26 (grassland)0.1–16 (forest)
1P
ryor et al., 20042
Duyzer et al., 1992
3F
inlayson-Pitts and P
itts, 1999
4A
sman, 2004
5S
einfeld and Pandis, 2006
6P
ryor et al., 2008
20
Yearly CAMx and CASTNet estimates of dry deposited N at RMNP for 2002
0.0
0.5
1.0
1.5
2.0
2.5
[HNO3,NO3,NH4] [HNO3,NO3,NH4] [Total N]
CASTNet CAMX CAMX
N D
ry D
epo
siti
on
[kg
/ha/
yr]
N-PNO3
N-PNH4
N-NOx
N-PAN
N-NxOy
N-Org N
N-NH3
N-HONO
N-HNO3
21
Summary
• Nitrogen deposition is increasing at RMNP –> ROMANS
• Numerous approaches applied to N source apportionment at RMNP
• Receptor models
• Deterministic models
• EOF analysis
• Hybrid approach
• No single technique will provide the entire answer – need to reconcile
22
Summary (cont’d)
• Can’t get enough simulated N to RMNP
• Nitric acid estimates not bad
• PM N (NH4 and NO3) underestimated
• Not capturing the late spring upslope event, although tracer transport ok
• Use ‘lagrangian process analysis’ to investigate this – chemistry, deposition or emissions?
23
Summary (cont’d)
• Accounting for ‘missing’ nitrogen can almost double the estimated dry deposition at RMNP for 2002 (1.2 vs 2.2 kg/ha/yr).
Species N-flux [kg/ha yr] contribution
HNO3 1.16 53%
NH3 0.60 28%
NxOy 0.22 10%
PAN + Org N 0.11 5%
Other N species 0.12 6%
24
25
CAMx bias relative to CASTNet:HNO3
0.000
0.050
0.100
0.150
0.200
0.250
0.300
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
2002
ug
-N/m
3
pred N-HNO3 [ug/m3] ob N-HNO3 [ug/m3]
0.000
0.020
0.040
0.060
0.080
0.100
0.120
0.140
0.160
0.180
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
2002
kg
-N/h
a
pred N-HNO3 DDep [kg/ha] ob N-HNO3 DDep [kg/ha]
26
0.000
0.050
0.100
0.150
0.200
0.250
0.300
0.350
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
2002
ug
-N/m
3
pred N-PNH4 [ug/m3] ob N-PNH4 [ug/m3]
0.000
0.005
0.010
0.015
0.020
0.025
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
2002
kg
-N/h
a
pred N-PNH4 DDep [kg/ha] ob N-PNH4 DDep [kg/ha]
CAMx bias relative to CASTNet:NH4+
27
0.000
0.050
0.100
0.150
0.200
0.250
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
2002
ug
-N/m
3
pred N-PNO3 [ug/m3] ob N-PNO3 [ug/m3]
0.000
0.002
0.004
0.006
0.008
0.010
0.012
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
2002
kg
-N/h
a
pred N-PNO3 DDep [kg/ha] ob N-PNO3 DDep [kg/ha]
CAMx bias relative to CASTNet:NO3+