1. ANALYSIS OF TROPOSPHERIC OBSERVATIONS FROM GOME AND TOMS Randall Martin, Daniel Jacob, Jennifer Logan, Paul Palmer Harvard University Kelly Chance, Thomas Kurosu Harvard-Smithsonian Center for Astrophysics

2. HOW DO COLUMNS OF TROPOSPHERIC NO 2 FROM GOME COMPARE WITH TRADITIONAL BOTTOM-UP NO x INVENTORIES? Emission NO h (440 nm) O 3, RO 2 NO 2 HNO 3 NO x lifetime 1 day NITROGEN OXIDES (NO x ) BOUNDARY LAYER ~ 2 km Tropospheric NO 2 column ~ E NOx Deposition GOME/SCIAMACHY NO / NO2   WITH ALTITUDE

3. RETRIEVAL OF TROPOSPHERIC NO 2 FROM GOME (errors  in 10 15 molecules cm -2 ) GOME SPECTRUM (423-451 nm) SLANT NO 2 COLUMN TROPOSPHERIC SLANT NO 2 COLUMN TROPOSPHERIC NO 2 COLUMN Fit spectrum Remove stratospheric contribution, diffuser plate artifact Use Central Pacific GOME data with: HALOE to test strat zonal invariance PEM-Tropics, GEOS-CHEM 3-D model to treat tropospheric residual Apply AMF to convert slant column to vertical column Use radiative transfer model with: local surface albedos from GOME local vertical shape factors from GEOS-CHEM global model local cloud info from GOMECAT          O 3, O 4, H 2 O, Ring, Undersampling, Common Mode Quantitative retrieval in partly cloudy scene

4. GEOS-CHEM MODEL Assimilated Meteorology (GEOS) 2 o x2.5 o (4 o x5 o ) horizontal resolution, 26 layers in vertical 24 tracers, 120 solved species, ~400 reactions describe tropospheric O 3 -NO x - hydrocarbon chemistry Heterogeneous chemistry (with off-line aerosol fields) Photolysis: Fast-J including aerosol scattering Emissions: –Fossil fuel: GEIA (NOx), Logan (CO), Piccot (NMHCs) –Biosphere: modified GEIA (hydrocarbons) & Yienger/Levy (soil NO x ) –Lightning: Price/Rind/Pickering, GEOS convective cloud tops –Interannually varying biomass burning (Logan, Duncan et al. 2002) Deposition: modified Wesely (dry), Liu/Mari (wet) Cross-tropopause transport: SYNOZ RECENT AND CURRENT APPLICATIONS: Tropospheric ozone : global budget, Asian outflow, U.S. air quality, Middle East, transatlantic transport, tropics (TOMS) Carbon monoxide: budgets, interannual variability Studies of Aerosols, Carbon dioxide, and Organics Satellite retrievals, inversions, data assimilation: CO, CO2, O3, HCHO, NO2 Chemical forecasting: TRACE-P, NOAA 2K2

5. GEOS-CHEM MODEL CAPTURES REGIONAL VARIATION IN NO GEOS-CHEM Aircraft Observations NO 2 number density

6. RETRIEVAL OF TROPOSPHERIC NO 2 FROM GOME GOME SPECTRUM (423-451 nm) SLANT NO 2 COLUMN TROPOSPHERIC SLANT NO 2 COLUMN TROPOSPHERIC NO 2 COLUMN Remove stratospheric contribution, diffuser plate artifact Use Central Pacific GOME data with: HALOE to test strat zonal invariance PEM-Tropics, GEOS-CHEM 3-D model to treat tropospheric residual

7. GEOS-CHEM MODEL IDENTIFIES FAVORABLE REGIONS TO DETERMINE STRATOSPHERIC COLUMN

8. BIAS THAT WOULD RESULT FROM THE ASSUMPTION OF ZERO TROPOSPHERIC NO 2 OVER THE PACIFIC Comparison with PEM-T observations of NO from aircraft suggests small model bias GEOS-CHEM Aircraft Observations NO 2 number density

9. TROPOSPHERIC NO 2 COLUMN FROM GOME AFTER REMOVING STRATOSPHERE AND DIFFUSER PLATE ARTIFACT, AND CORRECTING FOR THE PACIFIC BIAS 1996

10. RETRIEVAL OF TROPOSPHERIC NO 2 FROM GOME GOME SPECTRUM (423-451 nm) SLANT NO 2 COLUMN TROPOSPHERIC SLANT NO 2 COLUMN TROPOSPHERIC NO 2 COLUMN Apply AMF to convert slant column to vertical column Use radiative transfer model with: local surface albedos from GOME local vertical shape factors from GEOS-CHEM global model local cloud info from GOMECAT Quantitative retrieval in partly cloudy scene

11. IN SCATTERING ATMOSPHERE, AMF CALCULATION NEEDS EXTERNAL INFO ON SHAPE OF VERTICAL PROFILE d()d() IoIo IBIB EARTH SURFACE RADIATIVE TRANSFER MODEL Scattering weight ATMOSPHERIC CHEMISTRY MODEL “a-priori” Shape factor Tabulate w(  ) as function of: solar and viewing zenith angle surface albedo, pressure cloud optical depth, pressure INDIVIDUAL GOME SCENES NO 2 mixing ratio C NO2 (  )  (  ) is temperature dependent cross-section sigma (  )

12. CLOUDS SIGNIFICANTLY AFFECT SENSITIVITY OF GOME Clear-sky scattering weights Cloudy-sky scattering weights Shape factor

13. CLOUD REFLECTIVITY (R c ) AND CLOUD FRACTION (f) HAVE A LARGE INFLUENCE ON THE AMF Solar Zenith Angle Cloud Optical Thickness

14. Clear-sky AMF Fraction of I From Clouds (GOMECAT and LIDORT) Actual AMF accounting for clouds JULY 1996

15. VERTICAL COLUMNS LARGELY CONFINED TO REGIONS OF SURFACE EMISSIONS NO / NO2   WITH ALTITUDE NO x lifetime ~1day

16. GOME RETRIEVAL OF TROPOSPHERIC NO 2 vs. GEOS-CHEM SIMULATION (July 1996) GEIA & Logan emissions scaled to 1996

17. MODELS AND SATELLITE OBSERVATIONS: THE ODD COUPLE SATELLITE SPECTRA “L1 DATA” ATMOSPHERIC CONCENTRATIONS “L2 DATA” RETRIEVAL A PRIORI INFORMATION profile shape, Concentration range, Correlations… SCIENTIFIC ANALYSIS “L4 DATA” IN SITU OBSERVATIONS (“L1 DATA”) MODELS EVALUATION ASSIMILATION INCREASED KNOWELDGE INCEST?

18. DIAGNOSE MODEL CONTAMINATION OF RETRIEVAL BY CORRELATING AMF WITH VERTICAL COLUMN r = -0.14 r = -0.65 Negative correlation implies that AMF conversion to vertical columns will modify the slant column patterns to better fit the model Little relationship between AMF and enhanced NO 2 columns

19. CAN WE USE GOME TO ESTIMATE NO x 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 NO x GOME GEOS-CHEM (EPA emissions) GOME BIAS = +18% R = 0.78

20. NO 2 COLUMN FROM LIGHTNING SMALL COMPARED TO RETRIEVAL ERROR Error in Tropospheric NO 2 Column Retrieval 7-33x10 14 molecules cm -2 Tropospheric NO 2 Column Enhancement from Lightning (6 Tg N yr -1 ) for July (GEOS-CHEM)

21. We conclude that GOME is consistent with bottom-up NO x emissions inventories, but interesting differences remain … ? ? ? FiresBiosphereHuman activity Lightning Ocean Nitrogen oxides (NO x ) CO, Hydrocarbons h Ozone (O 3 ) h, H 2 O Hydroxyl (OH) What can we learn from TOMS about the relative roles of biomass burning, lightning, and dynamics in the distribution of tropical tropospheric ozone? TROPICAL TROPOSPHERIC OZONE LARGELY DETERMINES OXIDIZING POWER OF ATMOSPHERE

22. MOST LIGHTNING ACTIVITY IS OVER LAND

23. INTENSE BIOMASS BURNING OVER NORTHERN AFRICA DURING DJF

24. TROPOSPHERIC OZONE COLUMNS (Sep’96-Aug’97) TROPOSPHERIC OZONE COLUMNS (Sep’96-Aug’97) GEOS-CHEMTOMS (CCD) JJA SON MAM DJF R = 0.66 MODEL BIAS = -0.5 DU

25. EL NINO INTERANNUAL VARIABILITY IN OZONE: DIFFERENCE BETWEEN OCT 97 AND OCT 96 Chandra et al. [2002]

26. OZONE ENHANCEMENT FROM LIGHTNING (GEOS-CHEM) largely explains observed wave-1 pattern in TOMS ozone

27. SIMULATED OZONE CONCENTRATIONS AND FLUXES AT 300 hPa IN JAN 97 Incursion of northern hemispheric ozone over the South Atlantic through the “westerly duct” contributes to the wave-1 pattern

28. OZONE VERTICAL PROFILES OVER ABIDJAN North African Dec-Feb ozone enhancement from biomass burning Is seen by aircraft observations but not by TOMS MOZAIC aircraft data GEOS- CHEM TOMS (distributed w/assumed standard profile)

29. RAYLEIGH SCATTERING LIMITS SENSITIVITY OF TOMS TO SEASONAL VARIATION IN LOWER TROPOSPHERE TOMS sensitivity to ozone (LIDORT radiative transfer model) TOMS standard profiles S. Atlantic profile Abidjan profile

30. TOMS UNDERESTIMATES OZONE OVER BIOMASS BURNING REGIONS AND OVERESTIMATES OZONE OVER THE PACIFIC

31. CORRECTION FOR TOMS RETRIEVAL EFFICIENCY CANNOT EXPLAIN DISCREPANCY OVER ABIDJAN What do GOME and SCIAMACHY observe? TOMS (CCD) Corrected CCD TOMS (MR) GEOS-CHEM Tropopause 200 hPa MOZAIC (200 hPa) Month

32. SUMMARY WAVE-1 from Lightning What does GOME show? Surface NO x from GOME Accurate a-priori vertical profile and cloud info essential for nadir retrievals