NMHC emissions derived from GOME HCHO columns Paul Palmer, D. Jacob, A. Fiore, R. Martin Harvard University K. Chance and T. Kurosu Harvard-Smithsonian Center for Astrophysics Hydrocarbon emissions are important for understanding radical chemistry in the troposphere – source of HOx radicals Key Question: How do we validate satellite observations? http://www.people.fas.harvard.edu/~ppalmer

HCHO columns – July 1996 r2 = 0.7 n = 756 Bias = 11% GEOS-CHEM GOME [1016molec cm-2] GEIA isoprene emissions Model:Observed HCHO columns r2 = 0.7 n = 756 Bias = 11% [1012 atoms C cm-2 s-1]

Aircraft HCHO profile data North Atlantic Regional Experiment 1997 Southern Oxidant Study 1995 8 8 measurements Altitude [km] Altitude [km] 8 8 1.5 2.0 [ppb] Surface source (mostly isoprene+OH) Continental outflow

Relating HCHO columns to hydrocarbon emissions Chemical loss kHCHO Absence of transport  = Yi Ei HCHO  HC oxidation ki (HCHO yield Yi) i Emission Ei kHCHO HCi

HCHO yields from HCs Species 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 0.06 0.53 HCHO 0.15 1.64 CH3OH 2.1 23.0

Model HCHO column [1016 molec cm-2] model without isoprene July 1996 (25-50oN, 65-130oW) NW NE Slope S = Y/kHCHO Model HCHO column [1016 molec cm-2] SW SE model without isoprene Isoprene emission [1013 atomC cm-2 s-1]

Isoprene “volcano” GOME GEOS-CHEM [1016 molec cm-2] Temperature dependence of isoprene emission July 7 1996 Slant column [1016 mol cm-2] Surface temperature [K] July 20 1996 [1016 molec cm-2]

GOME isoprene emissions – July 1996 [1012 atom C cm-2 s-1]

Consistency: GOME and in situ data GEIA GOME r2 = 0.53 Bias -3% r2 = 0.77 Bias -12%

Global HCHO from GOME: July 1996 [1016 molec cm-2]