1. Rong-Ming Hu and Randall Martin Inspiring Minds

2. Retrieval of Aerosol Single Scattering Albedo (SSA)  Determined with radiative transfer calculation as SSA that reproduces TOMS Aerosol Index when constrained by MODIS aerosol optical depth and GEOS-CHEM aerosol vertical profile. MODIS AOD GEOS–CHEM Aerosol Profile LIDORT Calculated Observed (TOMS) AI TOMS AI

3. 331 nm and 360 nm

4. Optical depth at 360nm 1.50 0.01 11.11. 1.00 0.05

5. Aerosol profile from GEOS-CHEM and validation with ARM data Southern Great Plains, Lamont, Oklahoma (DOE/ARM site). Results are for 324 profiles from March, 2000 to March, 2003. Solid: GEOS-CHEM simulations. Asterisk, plus, diamond, triangle and square: NOAA/CMDL measurements.

6. Validation with in situ lidar data (April, 2001) Gobi Desert Dust Storm (MODIS). Solid: GEOS-CHEM simulations. Asterisk: lidar measurements in Cheju island (SNU, South Korea) Cheju

7. Aerosol Single Scattering Albedo from retrieval

8. Intercomparison with AERONET square: MAM, asterisk: JJA, triangle: SON, plus sign: DJF.

9. Sensitivity to Aerosol Optical depth and surface reflectivity Solid: surface reflectivity=0.05. Dashed: surface reflectivity=0.08. Dotted: surface reflectivity=0.15.

10. Uncertainty in retrieved ω 0 Parameter Input Uncertainty Retrieval Uncertainty TOMS AI ±0.01 ± 0.01 MODIS AOD 20% ± 0.05 land, 5% ± 0.03 ocean ± 0.08 Ångström exponent ±15 % ± 0.11 Surface reflectivity ±0.01 ± 0.02 Refractive index ±0.01 ± 0.02 Profile ±25 % ± 0.05 Combined ± 0.15

11. Conclusion  Low values of aerosol single scattering albedo near 0.8 occur in biomass burning and mineral dust regions.  Seasonal variation of single scattering albedo is associated with both mineral dust and biomass burning.  Retrieval results present  Retrieval results present a high degree of consistency with AERONET measurements; AERONET measurements; the correlation coeffcient, slope and intercept are 0.75, 0.93 and 0.078 respectively.   The dominant terms of retrieval uncertainty are the Ångström exponent, the aerosol optical depth and aerosol profiles contributing to a total uncertainty of 15 percent.