North American Isoprene Emissions

Measured from Space

Paul PalmerHarvard University

ACD seminar series, NCAR, January 14, 2002

Talk Overview

• Relating HCHO columns to VOC emissions

• Global 3d model analysis

• GOME HCHO columns

• Are different HCHO data consistent? •

• GOME isoprene emissions

Overall Approach

Talk Overview

• Relate HCHO columns to VOC emissions

• Global 3d model analysis

• HCHO from GOME

• Are different HCHO data consistent?

• GOME isoprene emissions

HCHO + h 2HO2 + CO

H2 + CO

HCHO + OH HO2 + CO + H2O

VOC + OH ... ... n HCHO + OTHER PRODUCTS

VOCs, HCHO and tropospheric O3

VOC

EPA BEIS2 isoprene

GEIAisoprene

ppb

Summertime in situ HCHO datasets

Fried et al 1997

Harris et al 1989

Kleindienst et al 1988

Lee et al 1995, 1998

Martin et al 1991

McKeen et al 1997

OZIE - Guenther

Reimer et al 1998

Shepson et al 1991

Relating HCHO columns to VOC emissions

•Absence of

transport = Yi Ei

iVOCi Emission Ei

kHCHO

kHCHO

HCHO yields from VOCsSpecies

Emission[TgC month-

1]

HCHO Yield[C-1]

Potential HCHO production [%]

CH4 2.6 1.0 28.5

ISOP 7.3 0.45 32.0

-pinenes

1.1 0.8

0.019 0.045

0.23 0.39

MBO 0.8 0.06 0.53

HCHO 0.15 1.0 1.64

CH3OH 2.1 1.0 23.0 Total: 86%

VOC YiHCHO

•Define a displacement length scale

and smearing length scale

ki

Horizontal transport displaces and smears HCHO signal

Limiting values:Ls,i U/ki when ki«kHCHO

Ls,i U/kHCHO when kHCHO«ki

midmorning eg values KHCHO = 0.5h-1; U = 20kmh-1; [OH]=5E6 mol cm-3

ISOP Ld,i & Ls,i 40 km

CH4 Ld,i & Ls,i = many 1000s km

CH3OH Ld,i =250 km; Ls,i = 1000 km

~ GOME obs

GEOS-CHEM global 3D model:

101

•Driven by GEOS met data

•2x2.5o resolution/26 vertical levels

•O3-NOx-VOC chemistry

•GEIA isoprene emissions

•Aerosol scattering: AOD:O3

Dickerson et al, [1997]

GEOS-CHEM HCHO columnsJuly 1996

[1016 molec cm-2]

GEIA isoprene emissions

NW NE

SESW

Isoprene emission [1013 atomC cm-2 s-1]

Mod

el H

CH

O c

olu

mn

[101

6 m

ole

c c

m-2

] July 1996 (25-50oN, 65-130oW)

Slope S = Y/kHCHO

n S[103 s]

r2 lifetime[hours]

Y[C-1]

NW 1810

2.04 0.51 1.67 0.34

NE 2193

1.90 0.43 1.76 0.30

SE 1913

2.09 0.65 1.48 0.39

SW 1750

1.27 0.49 1.48 0.24

Yields consistent with photochemical model

• Nadir-viewing SBUV instrument

• Launched April 1995

• Pixel 320 x 40 km2

• 10.30 am cross-equator time

• Global coverage in 3 days

• O3, NO2, BrO, OClO, SO2, HCHO, H2O, & cloud coverage

Global Ozone Monitoring Experiment

HCHO slant column fitting

3 x 1016 molec cm-2

8 x 1016 molec cm-2

1 fitting uncertainty 4 x 1015 molec cm-2

Chance et al [2000]

O3

NO2

BrO

O2-O2

vertical column = slant column /AMF

Palmer et al, [2001]

AMF example - Tennessee

GEOS-CHEM S()

w()

S() w()

AMFG

2.08

AMF

0.71

AMF calculation every GOME July 1996 scene...

GOME HCHO – July 1996

Chance et al, 2000; Palmer et al, 2001

Filtered for cloudy scenes (cf > 40%)

GOME HCHO – July 1996

Bias = 11%

r2 = 0.7 n = 756

GEOS-CHEM

GO

ME

GOME HCHO(T) vs ISOP(T)

ISOP(T) [Guenther et al, 1995]

300.5

Ozarks

Overall Approach

EPA BEIS2

GEIA

ppb

Summertime in situ HCHO datasets

Fried et al 1997

Harris et al 1989

Kleindienst et al 1988

Lee et al 1995, 1998

Martin et al 1991

McKeen et al 1997

OZIE -Guenther

Reimer et al 1998

Shepson et al 1991

Modeling in situ dataGEIA BEIS2

r2 = 0.53

Bias -3%

r2 = 0.65

Bias -30%

NW NE

SESW

Isoprene emission [1013 atomC cm-2 s-1]

Mod

el H

CH

O c

olu

mn

[101

6 m

ole

c c

m-2

]Model Transfer functions

GOME isoprene emissions

BEIS2 fine structure

Consistency: GOME and in situ data

r2 = 0.77

Bias -12%

Summary

New methodology for VOC emission from space-based HCHO columns

Isoprene is dominant VOC for North American summertime

GOME shows Ozarks isoprene volcano

EPA BEIS2 too low?

GOME consistent with in situ data

Daily VOC emissions: the future?

Acknowledgements

Daniel Jacob, Arlene Fiore, Randall Martin (Harvard University)

Kelly Chance, Thomas Kurosu (Harvard-Smithsonian Observatory)