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Simultaneous Retrievals of aerosol and surface from a combination of AERONET- MODIS-MISR-POLDER data

Simultaneous Retrievals of aerosol and surface from a combination of AERONET- MODIS-MISR-POLDER data. Algorithm: Oleg Dubovik 1 , Alexander Sinyuk 1 , MODIS: Yoram Kaufman 1 Eric Vermote 2 Jean-Claude Roger 2

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Simultaneous Retrievals of aerosol and surface from a combination of AERONET- MODIS-MISR-POLDER data

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  1. Simultaneous Retrievals of aerosol and surface from a combination of AERONET- MODIS-MISR-POLDER data Algorithm:Oleg Dubovik1, Alexander Sinyuk1, MODIS: Yoram Kaufman1 Eric Vermote2 Jean-Claude Roger2 MISR: John Martonchik3, Ralph Kahn3, Dave Diner3, POLDER: Francois-Marie Breon4, AERONET: Brent Holben1, Ilya Slutsker1 1- NASA/GSFC, Greenbelt, MD, USA 2 - UMD, Greenbelt, MD, USA 3 - NASA/JPL, CA, USA 4 - CEA/DSM/LSCE, France

  2. Retrieval of surface needsatmospheric correction for aerosol effect Retrieval of aerosol reliesonassumption of surface reflectance Idea:Less assumptions are needed in simultaneous retrieval of aerosol and surface from combination of up- and down - looking observations

  3. Retrieval using combinations of up-looking Ground-based and down-looking satellite observations Retrieved: Aerosol Properties: - size distribution - real ref. ind. - imag. ref. ind (AERONET sky channels) • Surface Parameters: • BRDF (MISR, POLDER) • Albedo (MODIS)

  4. AERONET- MISR - POLDER - MODIS data • AERONET Ground-based Sun-sky radiometer: - t(l) ± 0.02 at 6 channels: 0.34, 0.38, 0.44, 0.67, 0.87, 1.02, 1.65mm • I(l,Q) ± 0.05% at 4 channels: 0.38, 0.44, 0.67, 0.87, 1.02, 1.65mm 3° ≤ scattering angles ≤ ~70° • P(l,Q) ± 0.02% at 0.87 • MISR Reflectance at 4 channels: 0.45, 0.55, 0.67, 0.87 mm 9 viewing angles: ±70.5o, ± 60o,± 45.6o, ± 26.1o, 0o • MODIS Reflectance at 7 channels: 0.47, 0.55, 0.66, 0.87,1.2, 1.6, 2.1 • POLDER Reflectance at 7 channels: 0.44, 0.49, 0.56, 0.67,0.76, 0.87, 0.91 13 viewing angles Polarization at: 0.44, 0.67, 0.87

  5. Retrieval scheme: MISR, POLDER MODIS • Forward model: • - Detailed aerosol (same as in AERONET) • Multiple scattering accounts for BRDF • BRDF modeled using parameterized model • (Rahman-Pinty-Verstraete, 1993) Numerical inversion: -Accounting for noise -Solving Ill-posed problem - Setting a priori constraints Observations aerosol particle sizes, complex refractive index, parameters of BRDF (or Lambertian albedo)

  6. Inversion • Statistically Optimized Minimization- • Multi-term LSM Fitting (Dubovik and King 2000; Dubovik 2004) weighting Lagrange parameters • Measurements: • i=1 - optical thickness • i=2 - AERONET radiances • i=3 - stellite radiances • their covariances • (should depend on l and Q) • -lognormal error distributions a priori restrictions on norms of derivatives of: i=4 -size distr. variability; i=5 -n spectral variability; i=6 -k spectral variability; i=7 - surface reflectance spectral variability; consistency Indicator

  7. Questions & Issues: • Retrieved aerosol properties: • are there any improvements compare to conventional AERONET retrieval • Retrieved surface properties: • reliable? • are there any limitations? • what is the difference with conventional atmospheric correction?

  8. August 9, 2003 t(0.44) ~ 0.3 Simultaneous fitting AERONET MODIS

  9. Summer, 2003 MONGU Simultaneous fitting August 9, 2003 t(0.44) ~ 0.3 MISR-MODIS MISR MODIS

  10. Comparisons of Surface Retrievals (with improved vertical profile) Surface Albedo: Surface BRDF:

  11. Effect of Aerosol Vertical Distribution on the Surface Retrievals Assumed Profiles:

  12. Surface Effect on Retrievals of the Refractive Index (low aerosol loading) POLDER: June 24, 2003 t(0.44) ~ 0.26 , SZA=470 MISR: August 9, 2003 t(0.44) ~ 0.3, SZA=400

  13. Surface Effect on the Retrievals of the Size Distribution (low aerosol loading) MISR: August 9, 2003 t(0.44) ~ 0.3, SZA=400 POLDER: June 24, 2003 t(0.44) ~ 0.26 , SZA=470

  14. Surface Effect on the Retrievals at High Aerosol Loading POLDER: August 18, 2003 t(0.44) ~ 0.63, SZA=350

  15. Surface Effect on the Retrievals of Single Scattering Albedo MISR: August 9, 2003 t(0.44) ~ 0.3, SZA=400 POLDER: August 18, 2003 t(0.44) ~ 0.63, SZA=350

  16. Effect of Particle Non-Sphericityon the Retrievals June, 2003 Solar Village, Saudi Arabia

  17. Surface Effect on the Retrievals of Single Scattering Albedo (Almucantar inversion with corrected surface) POLDER: June 7, 2003 t(0.44) ~ 0.67 , SZA=700 POLDER: September 27, 2003 t(0.44) ~ 0.24 , SZA=700

  18. Retrievals for Islands or Costal sites Cape Verde (Island)

  19. Results: • Simultaneous inversion of satellite and AERONET data has been developed • Surface BRDF and Albedo can be retrieved simultaneously with aerosol (low and moderate t,) • Improved retrievals of aerosol: - refractive index and size (low tover vegetation) - wo(l) and size (over bright surface) • The approach is very useful for sites with complex surface structure (Islands, costal) Plans: • Completing analysis • Making operational retrievals • Including Lidar information

  20. Comparisons of MISR and POLDER geometries Mongu, August 7,9 ,10, 2003

  21. Almucantar and principle plane retrievals: Size Distribution POLDER: June 7, 2003 t(0.44) ~ 0.67 , PP: SZA=230; ALM: SZA=700 POLDER: September 27, 2003 t(0.44) ~ 0.24 , PP: SZA=340; ALM: SZA=700

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