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Quantifying Aerosol Types and Their Impact on Trace Gas Retrievals From Satellite Measurements

Vijay Natraj (California Institute of Technology) Hartmut Bösch (Jet Propulsion Laboratory) Yuk Yung (California Institute of Technology). Quantifying Aerosol Types and Their Impact on Trace Gas Retrievals From Satellite Measurements.

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Quantifying Aerosol Types and Their Impact on Trace Gas Retrievals From Satellite Measurements

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  1. Vijay Natraj (California Institute of Technology) Hartmut Bösch (Jet Propulsion Laboratory)Yuk Yung (California Institute of Technology) Quantifying Aerosol Types and Their Impact on Trace Gas Retrievals From Satellite Measurements AGU Fall Meeting December 4, 2005

  2. Photon path length is enhanced through multiple scattering by aerosols Incident light Light reaching the detector Aerosol Layer 1 Aerosol Layer 2 Ground surface Major Source of Retrieval Uncertainty AGU Fall Meeting December 4, 2005

  3. Global Aerosol Climatology Courtesy: Kahn et al, 2001 AGU Fall Meeting December 4, 2005

  4. Aerosol Optical Properties • Each mixing group is a combination of 4 different aerosol components from a basic set of 7 (Kahn et al., 2001). • Sulfate (land/water), seasalt, carbonaceous, black carbon: spherical => Mie code (de Rooij and van der Stap, 1984) • Mineral dust (accumulated/coarse): mixture of oblate and prolate spheroids => T-matrix code (Mishchenko and Travis, 1998) • Lognormal distribution • Polarization fully considered AGU Fall Meeting December 4, 2005

  5. Scattering Matrix (755 nm) AGU Fall Meeting December 4, 2005

  6. Forward Model Details • Park Falls, Wisconsin, July (SZA = 31 degrees) • Exponential drop-off in aerosol extinction (scale height: ~ 1 km, optical depth: 0.1) • OCO spectral regions • Forward model: RADIANT (Christi, CSU) + single scattering approximation for polarization • Lorentzian instrument lineshape function (resolving powers: O2A band: 17000, CO2 bands: 20000) AGU Fall Meeting December 4, 2005

  7. Weighting Functions (O2A Band) AGU Fall Meeting December 4, 2005

  8. Weighting Functions (Weak CO2 Band) AGU Fall Meeting December 4, 2005

  9. Weighting Functions (Strong CO2 Band) AGU Fall Meeting December 4, 2005

  10. Retrieval Groups: Single Scattering Albedo AGU Fall Meeting December 4, 2005

  11. Retrieval Groups: Normalized Extinction Coefficient AGU Fall Meeting December 4, 2005

  12. Sensitivity Tests • Measurement error: 0.43 ppm • Smoothing error: 0.29 ppm • Error due to incorrect assumption of aerosol type within retrieval group • Group 1: 0.27 ppm • Group 2: 0.02 ppm • Group 3: 0.03 ppm AGU Fall Meeting December 4, 2005

  13. Conclusions • Aerosol retrieval groups determined from basic aerosol mixing groups • Choosing incorrect mixing group within retrieval group leads to small errors • Need to test more scattering geometries to validate retrieval types • More realistic aerosol profiles need to be included AGU Fall Meeting December 4, 2005

  14. Acknowledgments • OCO L2 Team (JPL) • Matt Christi (CSU) • Michael Mishchenko (GISS) • Olga Kalashnikova and Ralph Kahn (JPL) AGU Fall Meeting December 4, 2005

  15. Related Talks/Posters • Charles Miller (A14C-02) • Hartmut Boesch (A12D-05) • Gretchen Aleks (A33B-0883) AGU Fall Meeting December 4, 2005

  16. Importance of Polarization • Need to consider both atmospheric/surface and instrumental polarization AGU Fall Meeting December 4, 2005

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