REPARTEE: Pollutant FluxesEiko Nemitz, Gavin Phillips, Chiara Di Marco, Daniela Famulari,

Carole Helfter, Rick Thomas, David Fowler: Centre for Ecology and Hydrology (CEH) Edinburgh

Claire Martin, James Dorsey, Martin Gallagher: SEAES, University of Manchester

Ben Langford, Brian Davison, Nick Hewitt: University of Lancaster

Janet Barlow, Curtis Wood: University of Reading

Sue Grimmond:Kings College London

A collaboration between NERC CityFlux and REPARTEE

Urban Flux Measurement Campaigns within CityFlux

MIRAGEMarch 2006

Mexico City (19,200,000)

June 2003

Boulder, CO(92,000)

GOTE2005Feb. 2005

Gothenburg(480,000)

CityFluxDecember 2005

Edinburgh(435,000)

CityFluxOctober 2006

London(7,500,000)

CityFluxMay 2006

Manchester (2,200,000)

Why Measure Urban Pollutant Fluxes?

• Direct measurement of emissions (unlike emissions derived from concentrations)

• Independent top-down verification of emission inventories (non reactive compounds)

• Source attribution (spatial & temporal)

• Identification of unknown sources

• Information on chemical processing (reactive compounds)

Micrometeorological Flux Measurement• Application of eddy

covariance approach to the urban environment (like CO2 forest flux towers in international networks)

• Derives vertical flux through the horizontal plane at measurement height

• Flux footprint averages over several km2

420360300240180120600

relative time [s]

15

10

5

0

NO

3- [g

m-3

]

-2

-1

0

1

w [m

s-1

]

420360300240180120600

NNNN χwχww'χ'F

up-draughts

down-draughts

Need a rapid (5 -10 Hz) measurement of concentration and wind components

Eddy Covariance

Flux Measurements During REPARTEE

Eddy-covariance fluxes:• CO2 (18 months)• CO• Volatile organic compounds (VOCs) – benzene, toluene,

methanol, acetone, isoprene, …• Particle Number (total, size-segregated)• Aerosol Chemical Components (NO3

-, SO42-, Org)

• Ozone (REPARTEE-I only)

Gradients (BT Tower vs. Regents Park):• Further aerosol components• O3, NO, NO2, SO2

Gradients above London (REPARTEE-I)

14

12

10

8

6

4

2

0

SO

42- A

MS

To

we

r [

g m

-3]

14121086420

SO42-

AMS Regent's Park [g m-3

]

y = 0.91x + 0.66

(R2 = 0.89)

(d) SO42-

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

Cl- A

MS

To

we

r [

g m

-3]

3.02.01.00.0

Cl- AMS Regent's Park [g m

-3]

y = 1.26x + 0.051

(R2 = 0.62)

(e) Cl-

16

14

12

10

8

6

4

2

0N

O3- A

MS

To

we

r [

g m

-3]

1612840

NO3- AMS Regent's Park [g m

-3]

y = 1.64x + 0.051

(R2 = 0.86)

(f) NO3-

14

12

10

8

6

4

2

0

Org

AM

S T

ow

er

[g

m-3

]

12840

Org AMS Regent's Park [g m-3

]

y = 0.61x - 0.054

(R2 = 0.81)

(c) OM50

40

30

20

10

0

O3

To

we

r [p

pb

]

50403020100

O3 Regent's Park [ppb]

y = 0.795x + 17.75

(R2 = 0.53)

(a) O3

60

50

40

30

20

10

0S

O2

To

we

r [

g m

-3]

6050403020100

SO2 Regent's Park [g m-3

]

y = 1.68 x + 0.410

(R2=0.76)

(b) SO2

How representative is the Park of the average concentration at ground level?

Fluxes of CO2 and H2O (average diurnal cycles)

0

10

20

30

40

50

60

0 5 10 15 20 25

Time of day (hours)

Fc

(μm

ol.m

-2.s

-1)

Winter

Spring

Summer

Autumn

0

10

20

30

40

50

60

70

0 5 10 15 20 25

Time of day (hours)

LE

(W

.m-2

)

Winter

Spring

Summer

Autumn

1. Lower CO2 net emissions in summer:- No heating related emissions- Net CO2 uptake by biosphere (parks, gardens)

2. Largest night-time emissions in winter, followed by spring- Highest heating related emissions

Weekday vs. Weekend

Source Attribution of Net CO2 Flux Winter Spring Summer Autumn

Raw Fc [tons CO2 km-2 month-1]

+ 1748 + 1640 + 1245 + 1730

Total natural gas consumption (FC-gas)

[tons CO2 km-2 month-1] &

Relative consumption [%]

+ 3127

50.8

+ 2530

55.7

+ 1810

34.5

+ 2498

31.5

Total biosphere exchange [tons CO2 km-2 month-1]

& Relative exchange [%]

-313

- 6.1

- 313

- 6.1

- 131

- 4.8

Total human exhalation [tons CO2 km-2 month-1]

& relative human

contribution [%]

+ 230

3.7

+ 230

5.1

+230

4.4

+230

2.9

Traffic (+ oil and coal combustion) [%]

45.5 45.4 67.2 70.4

Comparison of VOC Fluxes with NAEI

Diurnal Cyclesduring

REPARTEE-II

410400390380370360

CO

2 co

nc [

ppm

]

24181260

120

80

40

0

CO

2 flux [

mo

l m-2 s

-1]2000

1500

1000

500

0

CO

flu

x [n

g m

-2 s

-1]

120

80

40

0V

d (O3 ) [m

m/s]

12

8

4

0

Flu

x ra

tio C

O/C

O2 (

arb

. uni

ts)

Particle Number

Fluxes by CPC

(10 – 2000 nm)

Variability in Particle Number Flux

PMF Factor Analysisof Organic Aerosol (BT Tower)

“Cooking” OA

HOA

LV-OOA

LV-OOA-91?

Consistent with Regents Park measurements during REPARTEE: Allan et al., ACP, 2010.

10

8

6

4

2

0

Mass

2015105

Hour of Day

10

8

6

4

2

0

10

8

6

4

2

0

10

8

6

4

2

0

80x10-3

604020

0Frac

tion o

f sign

al

1009080706050403020

0.15

0.10

0.05

0.00

80

60

40

20

0

x10

-3

0.100.080.060.040.020.00

Q-AMS Fluxes (REPARTEE-I 2006)

600

400

200

0

FH

OA[

ng

m-2s-1

]

201612840

12x103

8

4

0

FC

O [n

g m

-2s-1]

40

20

0

-20FN

O3- [n

g m

-2s-1

]

-20

-10

0

10

20 FS

O4

2- [n

g m

-2s-1]

-40

-20

0

20

40F

OO

A [n

g m

-2s-1

]

400

300

200

100

0

Tra

ffic

2220181614121086420

1.2

0.8

0.4

0.0

OO

A [

ug

m-3]

2.0

1.5

1.0

0.5

0.0S

O4 2

- [ug

m-3]

1.0

0.8

0.6

0.4

0.2

0.0

NO

3- [u

g m

-3]

250

200

150

100

50

0

CO

pp

bv

3.0

2.0

1.0

0.0

HO

A [

ug

m-3]

400

300

200

100

0

Tra

ffic

Concentrations Fluxes

Traffic

HOA

CO

Nitrate

Sulfate

LV-OOA

800

600

400

200

0

Flu

x H

OA

ng

m-2

s-1

00:0025/10/2006

00:0026/10/2006

00:0027/10/2006

00:0028/10/2006

00:0029/10/2006

Time

35

30

25

20

15

10

5

0

Flu

x CO

ug

m-2 s

-1

600

500

400

300

200

100

0

Flu

x H

OA

ng

m-2

s-1

14x103121086420

Flux CO ng m-2

s-1

R2 = 0.62

y = 0.024x

Correlation between HOA and CO Fluxes (REPARTEE-I, Q-AMS)

Look out for: Phillips et al. in ACPD REPARTEE Special Issue

Comparison with Other CitiesDiurnal Cycles NO3

- & HOA

200

100

0

-100

24181260

1200

800

400

0

HO

A flu

x [ng

m-2 s

-1]

400

300

200

100

0

-100

HO

A f

lux

[ng

m-2

s-1

]

120

80

40

0

Manchester

London

Boulder

Gothenburg

40

20

0

24181260

200

150

100

50

0

-50

NO

3 - flux [n

g m-2 s

-1]

-40

-20

0

20

40

NO

3- flu

x [n

g m

-2 s

-1]

40

20

0

-20

Manchester

London

Boulder

Gothenburg

m/z

Comparison of Concentration vs. Flux Spectrum

NO2+

SO+

SO2+

CO2+

C4H9+

C4H7++ C3H3O+

C5H7++ C4H3O+

Exchange velocities (Campaign Average)Ve = Flux / Concentration

Take-Home Messages• First independent assessment of emission inventories

through direct flux measurements for London• Close agreement between measurements and NAEI for

CO2, CO and some VOCs (benzene / toluene)• Poor agreement for other oxygenated VOCs• Aerosol composition and diurnal pattern in organic

aerosol fluxes consistent with significant contribution from cooking (deep frying?)

• Urban area acts as a significant source for aerosol nitrate during certain conditions (cool, calm, high humdity)

• Flux measurements provide a further angle to probe chemical signature of local (primary) organic aerosol (ongoing).

Outlook

• Full publication in Atmos. Chem. Phys. REPARTEE Special Issue (online)

• ClearfLo long-term flux measurements 2010-2013:– CO

– CO2

– CH4 (first time)

– O3

– NO/NO2 (first time)

– Particle number