1. North American Isoprene Emissions Measured from Space
Paul Palmer
Harvard University
ACD seminar series, NCAR, January 14, 2002

2. Talk Overview Relating HCHO columns to VOC emissions
Global 3d model analysis
GOME HCHO columns
Are different HCHO data consistent? •
GOME isoprene emissions

3. Overall Approach

4. Talk Overview Relate HCHO columns to VOC emissions
Global 3d model analysis
HCHO from GOME
Are different HCHO data consistent?
GOME isoprene emissions

5. VOCs, HCHO and tropospheric O3
VOC + OH n HCHO + OTHER PRODUCTS
HCHO + h HO2 + CO
H2 + CO
HCHO + OH HO2 + CO + H2O

6. GEIA isoprene
EPA BEIS2 isoprene

7. 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
ppb

8. Relating HCHO columns to VOC emissions
kHCHO
Absence of transport  = Yi Ei  i
VOCi
Emission Ei
kHCHO

9. HCHO yields from VOCs Total: 86% Species Emission [TgC month-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
0.06
0.53
HCHO
0.15
1.64
CH3OH
2.1
23.0
Total:
86%

10. Horizontal transport displaces and smears HCHO signal
VOC YiHCHO
Define a displacement length scale
and smearing length scale
Horizontal transport displaces and smears HCHO signal ki

11. 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
CH Ld,i & Ls,i = many 1000s km
CH3OH Ld,i =250 km; Ls,i = 1000 km
~ GOME obs

12. 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]

13. GEOS-CHEM HCHO columns July 1996
GEIA isoprene emissions
GEOS-CHEM HCHO columns July 1996
[1016 molec cm-2]

14. Model HCHO column [1016 molec cm-2]
July 1996 (25-50oN, oW) NW NE
Slope S = Y/kHCHO
Model HCHO column [1016 molec cm-2] SW SE
Isoprene emission [1013 atomC cm-2 s-1]

15. Yields consistent with photochemical modelr2
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
0.24
Yields consistent with photochemical model

16. Global Ozone Monitoring Experiment
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

17. HCHO slant column fitting
Chance et al [2000] O3
NO2
BrO
O2-O2
3 x 1016 molec cm-2
8 x 1016 molec cm-2
1 fitting uncertainty 4 x 1015 molec cm-2

18. vertical column = slant column /AMF
Palmer et al, [2001]

19. AMF example - Tennessee
S() w()
AMF
0.71
AMFG
2.08
w()
GEOS-CHEM S()
AMF calculation every GOME July 1996 scene...

20. GOME HCHO – July 1996 Filtered for cloudy scenes (cf > 40%)
Chance et al, 2000; Palmer et al, 2001

21. GOME HCHO – July 1996
r2 = 0.7 n = 756
GOME
GEOS-CHEM
Bias = 11%

23. GOME HCHO(T) vs ISOP(T)
300.5
Ozarks
ISOP(T) [Guenther et al, 1995]

24. Overall Approach

25. GEIA
EPA BEIS2

26. 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
ppb

27. Modeling in situ data GEIA BEIS2 r2 = 0.65 Bias -30% r2 = 0.53

28. Model Transfer functionsNW NE
Model HCHO column [1016 molec cm-2] SW SE
Isoprene emission [1013 atomC cm-2 s-1]

29. GOME isoprene emissions

30. BEIS2 fine structure

32. Consistency: GOME and in situ data
r2 = 0.77
Bias -12%

33. 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?

34. Acknowledgements
Daniel Jacob, Arlene Fiore, Randall Martin (Harvard University)
Kelly Chance, Thomas Kurosu (Harvard-Smithsonian Observatory)