North American Isoprene Emissions Measured from Space

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 VOC + OH ... ... n HCHO + OTHER PRODUCTS HCHO + h 2HO2 + CO H2 + CO HCHO + OH HO2 + CO + H2O

6. GEIAisoprene 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%

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

11. Limiting values:Ls,i U/kiwhen ki«kHCHOLs,i U/kHCHOwhen kHCHO«ki midmorning eg values KHCHO = 0.5h-1; U = 20kmh-1; [OH]=5E6 mol cm-3 ISOP Ld,i & Ls,i 40 km CH4Ld,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 columnsJuly 1996 GEIA isoprene emissions [1016 molec cm-2]

14. July 1996 (25-50oN, 65-130oW) 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 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 uncertainty4 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 Bias -3%

28. Model Transfer functions NW 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)