1. SATELLITE OBSERVATIONS OF OZONE PRECURSORS FROM GOME
Randall Martin, Daniel Jacob,
Paul Palmer, Qinbin Li
Harvard University
Kelly Chance, Thomas Kurosu
Harvard-Smithsonian Center for Astrophysics

2. SURFACE OZONE ENHANCEMENTS CAUSED BY ANTHROPOGENIC EMISSIONS FROM DIFFERENT CONTINENTS
GEOS-CHEM model July 1997
North America
Europe
Asia
Li et al. [2002]

3. THE GOME SATELLITE INSTRUMENT
Launched in April 1995
Nadir-viewing solar backscatter instrument ( nm)
Low-elevation polar sun-synchronous orbit, 10:30 a.m. observation time
Field of view 320x40 km2, three cross-track scenes
Complete global coverage in 3 days

4. USE GOME MEASUREMENTS OF NO2 AND HCHO COLUMNS TO MAP NOx AND VOC EMISSIONS
BOUNDARY
LAYER
NO2
NO/NO2  
W ALTITUDE NO
HCHO CO OH
hours
hours
VOC
lifetime <1 day
HNO3
Emission
Emission
NITROGEN OXIDES (NOx)
VOLATILE ORGANIC CARBON (VOC)

5. RETRIEVAL OF TROPOSPHERIC NO2 FROM GOME (errors e in 1015 molecules cm-2)
GOME SPECTRUM ( nm)
SLANT NO2 COLUMN
TROPOSPHERIC SLANT NO2 COLUMN
TROPOSPHERIC NO2 COLUMN
Fit spectrum
e1 = 0.8
O3, O4, H2O, Ring
Use Central Pacific GOME data with:
HALOE to test strat zonal invariance
PEM-Tropics, GEOS-CHEM 3-D model to treat tropospheric residual
Remove stratospheric contribution, diffuser plate artifact
e2 = 0.4
Use radiative transfer model with:
local surface albedos from GOME
local vertical shape factors from GEOS-CHEM
local cloud info from GOMECAT
Apply AMF to convert slant column to vertical column
Quantitative retrieval for partly cloudy scenes
e3 =

6. CAN WE USE GOME TO ESTIMATE NOx EMISSIONS. TEST IN U. S
CAN WE USE GOME TO ESTIMATE NOx EMISSIONS? TEST IN U.S. WHERE GOOD A PRIORI EXISTS
Comparison of GOME retrieval (July 1996) to GEOS-CHEM model fields
using EPA emission inventory for NOx
GOME
BIAS = +18%
r = 0.78
NO/NO2  
WITH ALTITUDE
NOx lifetime
<1day
GEOS-CHEM
(EPA emissions)

7. GOME RETRIEVAL OF TROPOSPHERIC NO2 vs. GEOS-CHEM SIMULATION (July 1996)
GEIA & Logan
emissions
scaled to 1996

8. GEIA isoprene emissions
ISOPRENE MAIN SOURCE OF HCHO IN U.S. IN SUMMER HCHO columns – July 1996
Palmer et al.
GEOS-CHEM
GOME
[1016molec cm-2]
GEIA isoprene emissions
Model:Observed HCHO columns
r2 = 0.7
Bias = 11%
[1012 atoms C cm-2 s-1]

9. Model HCHO column [1016 molec cm-2] model without isoprene
GEOS-CHEM RELATIONSHIP BETWEEN HCHO COLUMNS AND ISOPRENE EMISSIONS IN N AMERICA Use relationship to map isoprene emissions from GOME observations NW NE
GEOS-CHEM
July 1996
Model HCHO column [1016 molec cm-2] SW SE
model without isoprene
Palmer
et al. [2002]
Isoprene emission [1013 atomC cm-2 s-1]

10. GOME GEIA GOME CONSISTENT WITH IN-SITU HCHO OBSERVATIONS r2 = 0.53
ISOPRENE EMISSIONS FOR JULY 1996 DETERMINED BY SCALING OF GOME FORMALDEHYDE COLUMNS [Palmer et al., 2002]
GOME
GOME
CONSISTENT WITH IN-SITU
HCHO OBSERVATIONS
GEIA
r2 = 0.53
Bias -3%
r2 = 0.77
Bias -12%

11. GOME TROPOSPHERIC SLANT COLUMNS DURING TRACE-P (3/15 - 4/15, 2001)
NO2
HCHO

12. NEXT STEP: COUPLED CHEMISTRY-AEROSOL MODEL Radiative and chemical (uptake HO2, NO2, NO3) effects of aerosols (SO4, BC, OC, Dust, Sea-Salt)
GEOS-CHEM March
 OH
 O3
Off-line aerosol fields from Ginoux et al. [2001] and Chin et al. [2002]

13. AEROSOLS REDUCE SURFACE O3 AND OH
GEOS-CHEM August
 OH
 O3
Off-line aerosol fields from Ginoux et al. [2001] and Chin et al. [2002]

14. Intercontinental O3 transport
CONCLUSIONS
Isoprene from GOME
Intercontinental O3 transport
NOx from GOME
OH and O3 from Aerosols