Comparison of the Optical Thickness and Ångström Exponent of the Aerosols Over the Ocean Retrieved from Direct Solar Radiation and Polarization Measurements by POLDER on Board ADEOS Satellite

Abstract

Direct solar radiation measurements were carried out on board in the Osaka Bay, on March 18, 1997, and at Sand Dune Agriculture Experiment Station, Ishikawa, on April 26, 1997. Based on those data, aerosol optical thickness at 550nm (τ_a550) and Angstrom exponent (α) were estimated. They were also retrieved from the degree of polarization at wavelengths of 443, 670, and 865 nm measured quasi-simultaneously by the POLDER sensor onboard the ADEOS satellite. The τ_a550 values retrieved from the degree of polarization were compared with those from the direct solar radiation measurements. The difference was about 0.03. The α values estimated from the degree of polarization were smaller than those from the direct solar radiation by 0.5 in typical cases.