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

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

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

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)

RETRIEVAL OF TROPOSPHERIC NO2 FROM GOME (errors e in 1015 molecules cm-2) GOME SPECTRUM (423-451 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 = 0.5-3.2

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)

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

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]

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]

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%

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

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]

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]

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