Constraining Emissions with Satellite Observations Daniel Jacob Paul Palmer Dorian Abbot Randall Martin Kelly Chance Thomas Kurosu Sushil Chandra Jerry Ziemke

PRESENT AND FUTURE SATELLITE OBSERVATIONS OF TROPOSPHERIC CHEMISTRY 2002 2002 2004 2004 2004 2004 2004 HCHO

CHALLENGE FOR THE NEXT DECADE: IMPROVE EMISSION INVENTORIES “Nova Scotians with lung problems should stay inside until pollution levels drop warned Environment Canada”

Historical records imply a large anthropogenic contribution to the present-day ozone background at northern midlatitudes Ozone trend from European mountain observations, 1870-1990 [Marenco et al.,1994] Major greenhouse gas Largely controls atmospheric oxidation Primary constituent of smog

? ? ? GLOBAL BUDGET OF TROPOSPHERIC OZONE 4900 4200 500 1200 Global sources and sinks, Tg O3 yr-1 (GEOS-CHEM model) Chem prod in troposphere 4900 Chem loss in troposphere 4200 Transport from stratosphere 500 Deposition 1200 ? Formaldehyde (HCHO) ? ? hv hv,H2O Nitrogen oxides (NOx) CO, VOCs Ozone (O3) Hydroxyl (OH) Fires Biosphere Human activity

BOTTOM-UP EMISSION INVENTORIES ARE NOTORIOUSLY DIFFICULT TO DETERMINE! Fuel use estimates Measurements of emission ratios Process studies Estimate biological density Temperature, water, … dependence of biological activity Extreme events "Trees cause more pollution than automobiles do."

HOW DO WE EVALUATE AND IMPROVE A PRIORI BOTTOM-UP INVENTORIES? Surface NOX Isoprene during July GEIA

TOP-DOWN INFORMATION FROM THE GOME SATELLITE INSTRUMENT Operational since 1995 Nadir-viewing solar backscatter instrument (237-794 nm) Low-elevation polar sun-synchronous orbit, 10:30 a.m. observation time Spatial resolution 320x40 km2, three cross-track scenes Complete global coverage in 3 days

USE GOME MEASUREMENTS TO RETRIEVE NO2 AND HCHO USE GOME MEASUREMENTS TO RETRIEVE NO2 AND HCHO COLUMNS TO MAP NOx AND VOC EMISSIONS GOME Tropospheric NO2 column ~ ENOx Tropospheric HCHO column ~ EVOC 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 COMPOUND (VOC)

PERFORM A SPECTRAL FIT OF SOLAR BACKSCATTER OBSERVATIONS absorption Solar Io Backscattered intensity IB l1 l2 wavelength Slant optical depth “Slant column” Scattering by Earth surface and by atmosphere 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 IN U.S. IN SUMMER K. Chance

SLANT COLUMNS OF NO2 FROM GOME Dominant stratospheric structure (where NO2 is produced from N2O oxidation) Also see tropospheric hot spots (fossil fuel and biomass burning) Remove strat & instrument artifacts using obs over Pacific

SLANT COLUMNS OF TROPOSPHERIC NO2 FROM GOME 1996

GEOS-CHEM MODEL Assimilated Meteorology (GEOS) 2ox2.5o horizontal resolution, 26 layers in vertical O3-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 ATMOSPHERIC CHEMISTRY MODEL “a priori” Shape factor dt() Io IB EARTH SURFACE sigma () NO2 mixing ratio CNO2() norm. by column ΩNO2 Scattering weight () is temperature dependent cross-section INDIVIDUAL GOME SCENES Calculate w() as function of: solar and viewing zenith angle surface albedo, pressure cloud optical depth, pressure, frac aerosol profile, type

VERTICAL COLUMNS CONFINED TO REGIONS OF SURFACE EMISSIONS Cloud artifacts removed by AMF calculation NO/NO2   WITH ALTITUDE NOx lifetime <1day

GEOS-CHEM Tropospheric NO2 GOME Tropospheric NO2 GEOS-CHEM Tropospheric NO2 r=0.75 bias 5% 1015 molecules cm-2

STRATEGY: OPTIMIZE INVENTORIES USING A PRIORI BOTTOM-UP AND GOME TOP-DOWN INFORMATION Retrieved emissions A priori emissions A posteriori emissions A priori errors Retrieval errors

TOP-DOWN ERROR IN NOX EMISSIONS GOME Spectrum (423-451 nm) Spectral fit and removal of stratospheric column 1x1015 molecules cm-2 Tropospheric NO2 Slant Column AMF (surface reflectivity, clouds, aerosols, NO2 profile) 42% of tropospheric column Tropospheric NO2 Column 30% of tropospheric column NOx Lifetime (GEOS-CHEM) NOx Emissions

TOP-DOWN INFORMATION FROM GOME REDUCES ERROR IN NOX EMISSION INVENTORY Bottom-up error a Top-down error r

OPTIMIZED NOX EMISSIONS

DIFFERENCE BETWEEN A POSTERIORI AND A PRIORI Annual mean ratio (A posteriori / A priori)

TROPOSPHERIC OZONE DETERMINED FROM TOMS/MLS SUGGESTS A PRIORI NOX EMISSIONS HIGH OVER INDIA Dobson Units for March, April, May TOMS/MLS Chandra et al. [2003] GEOS-CHEM

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

GOME (A posteriori) GEIA (A priori) EVALUATE GOME ISOPRENE INVENTORY BY COMPARISON WITH IN SITU OBSERVATIONS USING GEOS-CHEM MODEL AS INTERMEDIARY CONSISTENT WITH IN-SITU HCHO OBSERVATIONS GEIA (A priori) GOME (A posteriori) r2 = 0.53 r2 = 0.77 Palmer et al., 2003

GOME HCHO COLUMNS SHOW SEASONAL EVOLUTION OF VOC EMISSIONS D. Abbot APR JUL MAY AUG JUN SEP

TOP-DOWN INFORMATION FROM GOME IMPROVES BOTTOM-UP INVENTORIES Higher spatial resolution provided by SCIAMACHY