1. Randall Martin Space-based Constraints on Emission Inventories of Nitrogen Oxides Chris Sioris, Kelly Chance (Smithsonian Astrophysical Observatory) Lyatt Jaeglé (Univerisity of Washington) Tom Ryerson (NOAA)

2. Relative Uncertainty Global Surface NO x Emissions Uncertain to Factor of 2 Implications for Tropospheric Ozone, Aerosols, Indirect Effect, Nutrient Delivery Here in Tg N yr -1 (based on) Fossil Fuel 24 (GEIA) Biomass Burning 6 (Duncan et al., 2003) Soils 5 (Yienger and Levy, 1995) NOx Emissions (Tg N yr -1 ) Fossil Fuel (20-33) Biomass Burning (3-13) Soils (4-21)

3. Top-Down Information from the GOME and SCIAMACHY Satellite Instruments Nadir-viewing solar backscatter instruments including ultraviolet and visible wavelengths Low-elevation polar sun-synchronous orbit, late morning observation time GOME 1995-2002 Spatial resolution 320x40 km 2 Global coverage in 3 days SCIAMACHY 2002-present Spatial resolution 60x30 km 2 Global coverage in 6 days

4. Cloud-filtered Tropospheric NO 2 Columns Determined from SCIAMACHY May-Oct 2004 detection limit Retrieval based on Martin et al., 2002, 2003 Retrieval: Spectral fit Remove stratosphere Account for scattering

5. Error weighting Conduct a Chemical Inversion & Combine Top-Down and Bottom-up Inventories with Error Weighting A posteriori emissions Top-Down Emissions 10 15 molec cm -2 A Priori NOx Emissions SCIAMACHY NO 2 Columns 10 11 molec N cm -2 s -1 GEOS-CHEM model NO / NO2   W ALTITUDE

6. May-Oct 2004 48 Tg N yr -1 48 – 39 Tg N yr -1 A Posteriori Emission Inventory Reveals Major Discrepancy in NOx Emissions from Megacities GEIA r 2 =0.82 vs a priori

7. ICARTT: COORDINATED ATMOSPHERIC CHEMISTRY CAMPAIGN OVER EASTERN NORTH AMERICA AND NORTH ATLANTIC IN SUMMER 2004 International, multi-agency collaboration targeted at regional air quality, pollution outflow, transatlantic transport, aerosol radiative forcing Terra ERS MISR, MODIS, MOPITT ERS-2 GOME Envisat SCIAMACHY Aqua AIRS, MODIS NASA DC-8 UK BAE-143 DLR Falcon NOAA-P3 Canada Convair NASA Proteus

8. Large Change in NOx Emissions Near New York City 10 11 atoms N cm -2 s -1  10 11 atoms N cm -2 s -1 A prioriA posteriori A posteriori – A priori 8.3 Tg N 1.1 Tg N r 2 = 0.92 Evaluate Each Inventory By Conducting GEOS-CHEM Simulation & Sampling Model Along Aircraft Flight Tracks  NO x (ppbv) Simulation with A Posteriori – Simulation with A Priori  HNO 3 (ppbv) 7.2 Tg N

9. In Situ Airborne Measurements Support Top-Down Inventory In Situ GEOS-CHEM (A priori) GEOS-CHEM (A posteriori) New EnglandNew England + GulfRemote P-3 Measurements from Tom Ryerson (NOAA)

10. Speciated Inventory for Soil emissions A posteriori 70% larger than a priori! A priori A posteriori Largest soil emissions: seasonally dry tropical + fertilized cropland ecosystems (±200%) (±90%) r 2 = 0.62 Soils Onset of rainy season: Pulsing of soil NO x ! North Eq. Africa Jaeglé et al., 2005

11. Conclusions Growing confidence in top-down constraint on NOx emissions Gross-underestimate in NOx emissions from megacities Soil NOx emissions underestimated, especially from Northern Equatorial Africa Funding: National Aeronautics and Space Administration (NASA) Canadian Foundation for Innovation (CFI) Nova Scotia Research and Innovation Trust (NSRIT) Natural Sciences and Engineering Research Council of Canada (NSERC)