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Simultaneous retrieval of Aerosol and Chlorophyll from MODIS Aqua radiances

Simultaneous retrieval of Aerosol and Chlorophyll from MODIS Aqua radiances. Clark Weaver GEST UMBC NASA Goddard Arlindo da Silva GMAO Radiative Transfer Dave Flitner Zia Ahmad Chlorophyll Watson Gregg . Introduction.

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Simultaneous retrieval of Aerosol and Chlorophyll from MODIS Aqua radiances

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  1. Simultaneous retrieval of Aerosol and Chlorophyll from MODIS Aqua radiances Clark Weaver GEST UMBC NASA Goddard Arlindo da Silva GMAO Radiative Transfer Dave Flitner Zia Ahmad Chlorophyll Watson Gregg

  2. Introduction Goal: Construct algorithm that simultaneously retrieves Aerosol and Ocean Chlorophyll. Simulates observed MODIS radiances Observations, Reflectances 7 MODIS-Aqua level-2 channels (0.47 - 2.1um ) 2 Additional level-1b (0.412, 0.443, 0.488) Forward Model • Aerosol 3D Transport MODEL (GOCART) provides spatial and size distribution of aerosols • 3D Ocean Biogeochemical model provides first guess chlorophyll concentrations (Watson Gregg) • Herman Radiative Transfer Model (Vector Code) converts aerosol chlorophyll concentrations to reflectance

  3. Motivation Desire to retrieve absorbing aerosol information over Ocean using MODIS Radiances Need to account for chlorophyll absorption Approach: Use model based retrieval to use In Assimilation System

  4. RT Forward Model RT Forward Model Biogeochemical Ocean Model First guess 3D aerosol concentrations of Aerosol and Chlorophyll GOCART wf Aerosol Optical Parameters First guess Aerosol and Chlorophyll ρf First Guess Reflectance MODIS Observed Level 2 and 1b Reflectance ρo RETRIEVAL Adjust aerosol and chlorophyll wa Analysis 3D aerosol And chlorophyll concentrations Retrieved Aerosol and Chlorophyll ρa

  5. Radiative Transfer Forward model Many look-up-tables per MODIS channel generated by the University of Arizona radiative transfer model Variants: Aerosol species, Relative humidity Species Dust (dry Reff = 1.0, 1.4 µm) Seasalt (dry Reff = 1.0, 1.3 µm) Sulfate Black Carbon-Organic Carbon mixtures Variant: Chlorophyll Spectral Absorption from Morel and Maritorena (2001) Variants: Underlying Surface Properties Rough Ocean (2, 6, 12 m/s wind speeds Ocean wind speed is from GMAO meteorological assimilation

  6. Observed Radiance mg /m3 Total Analysis Radiance term mg /m3 Analysis Chlorophyll Radiance term

  7. Low Chlorophyll - Low aerosol

  8. High Chlorophyll - High aerosol

  9. Low Chlorophyll Moderate aerosol

  10. High Chlorophyll - High aerosol

  11. How well can we simulate the observe radiances?

  12. How well can we simulate the observe radiances?

  13. Black Carbon Organic Carbon Is the Analysis remembering the First Guess species distribution ? Black Carbon Organic Carbon

  14. Sulfate Dust Is the Analysis remembering the First Guess species distribution ? Sulfate Dust

  15. Sea salt Sea salt

  16. High AOD Solid chlorophyll = 0.04 mg/m3 Dashed chlorophyll = 0.20 mg/m3 SSA=0.95 Low Chlorophyll High Chlorophyll SSA=0.71

  17. Moderate AOD High AOD Solid chlorophyll = 0.04 mg/m3 Dashed chlorophyll = 0.20 mg/m3 SSA=0.95 Low Chlorophyll High Chlorophyll SSA=0.71

  18. Current Directions Developing Look-up-tables for absorbing aerosol and chlorophyll Chlorophyll=0.1 Absorbing AOD=0.1  Chlorophyll=0.1 +Absorbing AOD=0.1 Neural networks to replace Look-up-tables Model base retrieval algorithm

  19. Chlorophyll (simulated) from Biogeochemical model 1 September 2001

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