RETRIEVAL AND INTERPRETATION OF OZONE PRECURSORS USING THE

RETRIEVAL AND INTERPRETATION OF OZONE PRECURSORS USING THE GOME SATELLITE INSTRUMENT Randall Martin Kelly Chance Thomas Kurosu Chris Sioris Daniel Jacob Dorian Abbot Paul Palmer La. RC Air Quality Applications Group Sushil Chandra Jerry Ziemke Jim Szykman

HOW DO WE EVALUATE AND IMPROVE A PRIORI BOTTOM-UP INVENTORIES? Surface NOX Isoprene during July North American Isoprene Emissions (3 -15 Tg C yr-1) Global NOx Emissions (Tg N yr-1) GEIA Fossil Fuel 24 (20 -33) Biomass Burning 6 (3 -13) Soils 5 (4 -21)

TOP-DOWN INFORMATION FROM THE GOME SATELLITE INSTRUMENT • Operational since 1995 • Nadir-viewing solar backscatter instrument (237 -794 nm) • Low-elevation polar sunsynchronous orbit, 10: 30 a. m. observation time • Spatial resolution 320 x 40 km 2, three cross-track scenes • Complete global coverage in 3 days

USE GOME MEASUREMENTS TO RETRIEVE NO 2 AND HCHO COLUMNS TO MAP NOx AND VOC EMISSIONS GOME Tropospheric NO 2 column ~ ENOx Tropospheric HCHO column ~ EVOC BOUNDARY LAYER NO/ NO 2 NO NO 2 hours W ALTITUDE lifetime <1 day CO HCHO hours OH VOC HNO 3 Emission NITROGEN OXIDES (NOx) Emission VOLATILE ORGANIC COMPOUND (VOC)

PERFORM A SPECTRAL FIT OF SOLAR BACKSCATTER OBSERVATIONS absorption Solar Io Backscattered intensity IB l 1 l 2 wavelength Slant optical depth Scattering by Earth surface and by atmosphere “Slant column” EARTH SURFACE

GOME HCHO SLANT COLUMNS (JULY 1996) Hot spots reflect high VOC emissions from fires and biosphere BIOGENIC ISOPRENE IS THE MAIN SOURCE OF HCHO OVER U. S. IN SUMMER K. Chance

SLANT COLUMNS OF NO 2 FROM GOME Dominant stratospheric structure (where NO 2 is produced from N 2 O oxidation) Also see tropospheric hot spots (fossil fuel and biomass burning) Remove strat & instrument artifacts using obs over Pacific Martin et al. , 2002

SLANT COLUMNS OF TROPOSPHERIC NO 2 FROM GOME 1996 Martin et al. , 2002

GEOS-CHEM MODEL • • • Assimilated Meteorology (GEOS) 2 ox 2. 5 o horizontal resolution, 26 layers in vertical O 3 -NOx-hydrocarbon chemistry Radiative and chemical effects of aerosols Emissions: – Fossil fuel: GEIA (NOx), Logan (CO), Piccot (NMHCs) – Biosphere: modified GEIA (hydrocarbons) & Yienger/Levy (soil NOx) – Lightning: Price/Rind/Pickering, GEOS convective cloud tops – Interannually varying biomass burning • Cross-tropopause transport • Deposition

IN SCATTERING ATMOSPHERE, AMF CALCULATION NEEDS EXTERNAL INFO ON SHAPE OF VERTICAL PROFILE RADIATIVE TRANSFER MODEL “a priori” Shape factor Io sigma ( ) IB ATMOSPHERIC CHEMISTRY MODEL dt( ) EARTH SURFACE Scattering weight ( ) is temperature dependent cross-section Calculate w( ) as function of: • solar and viewing zenith angle • surface albedo, pressure • cloud optical depth, pressure, frac • aerosol profile, type NO 2 mixing ratio CNO 2( ) norm. by column ΩNO 2 INDIVIDUAL GOME SCENES

JULY 1996 Clear-sky NO 2 AMF Fraction of IB From Clouds Actual NO 2 AMF accounting for clouds Martin et al. , 2002

AEROSOLS REDUCE SENSITIVITY OF GOME TO TROPOSPEHRIC NO 2 BY UP TO 40% OVER BIOMASS BURNING REGIONS

VERTICAL COLUMNS CONFINED TO REGIONS OF SURFACE EMISSIONS Cloud/albedo artifacts removed by AMF calculation NO/ NO 2 WITH ALTITUDE NOx lifetime <1 day No clear lightning signal Martin et al. , 2002

GOME Tropospheric NO 2 GEOS-CHEM Tropospheric NO 2 r=0. 75 bias 5% Martin et al. , 2003 1015 molecules cm-2

STRATEGY: OPTIMIZE INVENTORIES USING A PRIORI BOTTOM-UP AND GOME TOP-DOWN INFORMATION Top-down emissions A priori emissions A posteriori emissions A priori errors Top-down errors Martin et al. , 2003

TOP-DOWN ERROR IN NOX EMISSIONS GOME Spectrum (423 -451 nm) Spectral fit and removal of stratospheric column 1 x 1015 molecules cm-2 Tropospheric NO 2 Slant Column AMF (surface reflectivity, clouds, 40% of tropospheric column aerosols, NO 2 profile) Tropospheric NO 2 Column NOx Lifetime (GEOS-CHEM) 30% of tropospheric column NOx Emissions Martin et al. , 2003

TOP-DOWN INFORMATION FROM GOME REDUCES ERROR IN NOX EMISSION INVENTORY Bottom-up error a Mean = 2. 0 Top-down error t Mean = 2. 0 Martin et al. , 2003

OPTIMIZED NOX EMISSIONS 36. 4 Tg N yr-1 37. 7 Tg N yr-1 Martin et al. , 2003

DIFFERENCE BETWEEN A POSTERIORI AND A PRIORI Annual mean ratio (A posteriori / A priori) Martin et al. , 2003

TOMS/MLS TROPOSPHERIC OZONE CONFIRMS A PRIORI BIOMASS BURNING NOX EMISSIONS HIGH OVER INDIA 30 N Dobson Units for March, April, May TOMS/MLS 30 N GEOS-CHEM 30 S Chandra et al. , 2003

IMPROVE INVENTORIES OF SOIL NOX EMISSIONS GOME Tropospheric NO 2 Columns

QUANTIFY INTERANNUAL VARIATION IN NOx EMISSIONS 1997 DJF MAM JJA SON 1998 1999 2000

TEMPORAL VARIATION OF GOME NO 2 COLUMNS OFTEN CONSISTENT WITH SURFACE OBSERVATIONS La. RC Air Quality Applications Group and Jim Szykman (EPA)

TROPOSPHERIC NO 2 DETERMINED FROM SCIAMACHY BY LIMB-NADIR MATCHING SCIAMACHY Spatial Resolution 7 Times Finer Than GOME

ISOPRENE EMISSIONS FOR JULY 1996 DETERMINED FROM GOME FORMALDEHYDE COLUMNS GOME COMPARE TO… GEIA (IGAC inventory) Palmer et al. , 2003

EVALUATE GOME ISOPRENE INVENTORY BY COMPARISON WITH IN SITU OBSERVATIONS USING GEOS-CHEM MODEL AS INTERMEDIARY GEIA (A priori) r 2 = 0. 53 CONSISTENT WITH IN-SITU HCHO OBSERVATIONS GOME (A posteriori) r 2 = 0. 77 Palmer et al. , 2003

GOME HCHO COLUMNS SHOW SEASONAL VOC EMISSIONS GOME -0. 5 GEOS-CHEM (GEIA) GOME GEOS-CHEM (GEIA) MAR JUL APR AUG MAY SEP JUN OCT 0 1016 molec cm-2 2. 0 2. 5 Agreement in general pattern, regional discrepancies point to need for improving GEOS-CHEM isoprene emissions (in progress using GBEIS) Abbot et al. , 2003

HCHO INTERANNUAL VARIATION HIGHLY TEMPERATURE SENSITIVE 1995 1996 1997 1999 2000 2001 1998 Abbot et al. , 2003

PRESENT AND FUTURE SATELLITE OBSERVATIONS OF TROPOSPHERIC CHEMISTRY multiple Platform ERS-2 Terra ENVISAT Space station Aura Sensor TOMS AVHRR/ GOME Sea. WIFS MOPITT MODIS/ SCIAMA MISR CHY MIPAS SAGE-3 TES Launch 1979 1999 2002 2004 N/L L L N/L L O 3 1995 1999 N CO 2 2002 OMI MLS CALIPSO 2004 N/L N 2004 N/L HNO 3 N L CH 4 L N/L N HCHO N N/L N SO 2 N N/L N Br. O N N/L N HCN L N N 2005 N L N OCO L N/L NO 2 TBD N/L NO aerosol TBD L Increasing spatial resolution N N