1. 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?

2. 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]

3. 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

4. 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

5. 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

6. Model HCHO column [1016 molec cm-2] model without isoprene
July 1996 (25-50oN, oW) 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]

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

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

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

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