SATELLITE OBSERVATIONS OF OZONE PRECURSORS FROM GOME

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

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 (237-794 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 COLUMNSTO MAP NOx AND VOC EMISSIONS GOME 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. GOME SPECTRUM (423-451 nm) SLANT NO2 COLUMN TROPOSPHERIC SLANT NO2 COLUMN TROPOSPHERIC NO2 COLUMN RETRIEVAL OF TROPOSPHERIC NO2 FROM GOME(errors e in 1015 molecules cm-2) 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 = 0.5-3.2

6. 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 NO2vs. GEOS-CHEM SIMULATION (July 1996) GEIA & Logan emissions scaled to 1996

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

9. GEOS-CHEM RELATIONSHIP BETWEEN HCHO COLUMNS AND ISOPRENE EMISSIONS IN N AMERICAUse 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. ISOPRENE EMISSIONS FOR JULY 1996 DETERMINED BY SCALING OF GOME FORMALDEHYDE COLUMNS [Palmer et al., 2002] GOME CONSISTENT WITH IN-SITU HCHO OBSERVATIONS GOME 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 MODELRadiative 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. CONCLUSIONS Isoprene from GOME Intercontinental O3 transport NOx from GOME OH and O3 from Aerosols