Chris Sioris Kelly Chance Space-Based Constraints on NOx Emissions and Aerosol Single Scattering Albedo Chris Sioris Kelly Chance Randall Martin Aaron Van Donkelaar Lyatt Jaeglé

Global Surface NOx Emissions Uncertain to Factor of 2 Implications for Tropospheric Ozone, Aerosols, and Indirect Effect GEIA Duncan et al. Yienger and Levy A priori Bottom-up errors estimated by comparing surface NOx emission inventory used here with an independent inventory (EDGAR). Top-down errors very conservative estimate based on processes. Top-down errors will be reduced in the future. Relative Uncertainty

SCIAMACHY/GOME Spectral Measurement Regions 30 km x 60 km 40 km x 320 km

Spectral Fit of NO2 Nonlinear least-squares fitting Distinct NO2 Spectrum Solar Io Ozone Backscattered intensity IB NO2 Scattering by Earth surface and by atmosphere Albedo A O2-O2 Nonlinear least-squares fitting

Perform a Radiative Transfer Calculation to Account for Viewing Geometry and Scattering Cloud Screening: Remove Scenes with IB,c > 0.7*IB,o IB,o IB,c Io q FRESCO Clouds Fields [Koelemeijer et al., 2002] Surface Reflectivity [Koelemeijer et al., 2003] LIDORT Radiative Transfer Model [Spurr et al., 2002] Rc Ro Pc dt Rs

Cloud-filtered Tropospheric NO2 Columns Observed from the SCIAMACHY Satellite Instrument (Data  ICARTT) Lifetime ~ hours NO/NO2   W ALTITUDE May-Sept 2004 detection limit

Major Urban Centers Are Concentrated NOx Sources May-Sept 2004 detection limit

SPACE-BASED CONSTRAINTS ON NOx EMISSIONS Tropospheric NO2 Columns GOME GEOS-CHEM model (GEIA) JJA 1997 r = 0.75 bias=5% 1015 molecules cm-2 Martin et al. [2003] Error weighting A priori emissions (GEIA) A posteriori emissions Difference

43 Tg N May-Sept 2004 43 - 38 Tg N SCIAMACHY minus a priori

Satellite Observations of Soil NOx Emissions from Sahel 40% of African NOx Emissions from Soils Results for the year 2000 Jaeglé, Martin, et al., JGR, 2004

Aerosol Single Scattering Albedo Major Source of Uncertainty in Global Radiative Forcing Estimates IPCC [2001]

Maximum Sensitivity to Aerosol Optical Thickness Over Dark Surfaces More Sensitive to Single Scattering Albedo Over Bright Surfaces Saharan Dust Plume Staten Island Refinery Fire King et al., BAMS, 1999

TOMS Aerosol Index Measures Absorbing Aerosols In Ultraviolet Where Rayleigh Scattering Acts as Bright Surface July TOA spectral albedo measured by GOME

MODIS Optical Depth Includes Both Scattering and Absorbing Aerosols Requires aerosol size distribution information (AERONET and GEM-AQ) Aerosol relative vertical distribution (LIDAR, GEM-AQ) Use radiative transfer model to calculate SSA that reproduces observed Aerosol Index July 2000 MODIS AOD at 470 nm July 2000

Funding Canadian Foundation for Climate and Atmospheric Sciences (CFCAS) Natural Sciences and Engineering Research Council of Canada (NSERC) National Aeronautics and Space Administration (NASA) Canadian Foundation for Innovation (CFI) Nova Scotia Research and Innovation Trust (NSRIT)