North American Isoprene Emissions Measured from Space Paul Palmer Harvard 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

VOCs, HCHO and tropospheric O3 VOC + OH ... ... n HCHO + OTHER PRODUCTS HCHO + h 2HO2 + CO H2 + CO HCHO + OH HO2 + CO + H2O

GEIA isoprene EPA BEIS2 isoprene

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

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

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%

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

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

Model HCHO column [1016 molec cm-2] 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]

Yields consistent with photochemical model 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 0.24 Yields consistent with photochemical model

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

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

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

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

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

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

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

Overall Approach

GEIA EPA BEIS2

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

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

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

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)