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Retrieval of SO 2 Vertical Columns from SCIAMACHY and OMI: Air Mass Factor Algorithm Development and Validation. Chulkyu Lee , Aaron van Dokelaar, Gray O’Byrne: Dalhousie Univ. Randall V. Martin: Dalhousie Univ. and Harvard-Smithsonian Nickolay Krotkov: NASA Goddard and UMBC
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Retrieval of SO2 Vertical Columns from SCIAMACHY and OMI: Air Mass Factor Algorithm Development and Validation Chulkyu Lee, Aaron van Dokelaar, Gray O’Byrne: Dalhousie Univ. Randall V. Martin: Dalhousie Univ. and Harvard-Smithsonian Nickolay Krotkov: NASA Goddard and UMBC Andreas Richter: Univ. of Bremen Greg Huey: Georgia Tech John S. Holloway: NOAA May 28, 2009
IB Io dτ(η) Earth Surface Local AMF Calculation Geometric AMF: Shape factor eta (η) Radiative Transfer Model (LIDORT) Atmospheric Chemistry Model (GEOS-Chem) SO2 mixing ratio, CSO2(η) Scattering weight • Calculate ω(η) as function of: • solar and viewing zenith angle (θs, θv) from OMI, SCIAMACHY • surface reflectivity (TOMS Climatology) • pressure, aerosol from GEOS-Chem • Clouds, O3 column from OMI, SCIAMACHY For individual scenes
GEOS-Chem Simulation • GEOS-Chem v8-01-04 • - GEOS-4, 30 η vertical levels, 2º latitude by 2.5º longitude • - Based on EDGAR inventory • - Regional inventories: NEI99, BRAVO, CAC, Streets, EMEP
Shape Factor: GEOS-Chem vs In-situ Differences would change AMF by <10% In-situ platform DC-8 & C-130
OMI SO2 AMF for 2006 • Calculated at 313.2 nm; Cloud Radiance Fraction < 0.2; SZA < 70 • SCIAMACHY AMF at 319.7 nm within 25%
Local AMF Increases Agreement with Aircraft ▲ INTEX-A ■ INTEX-B
SO2 Vertical Columns for 2006 Correlation with GEOS-Chem (GC) : Globally r ~0.78 : ~0.84 over US : ~0.83 over China GC with OMI AMF within 10% GC with SCIAMACHY AMF Cloud Radiance Fraction < 0.2; SZA < 70
Sensitivity of Retrieved SO2 to ΔEmissions GEOS-Chem SO2 changes by ×2 OMI SO2 AMF changes < 30%
Summary • Local AMFs improve agreement of OMI and SCIAMACHY with in-situ • Validation of SO2 vertical columns from SCIAMACHY and OMI with airborne in-situ measurements for INTEX-A and B • : r = 0.9 • Validation of GEOS-Chem SO2 shape factors • with airborne in-situ measurements for INTEX-A and B • : <10% change in AMF • Large signal from anthropogenic emissions in retrieved SO2 columns