A method for determining atmospheric optical parameters and surface albedo from multiangle satellite measurements: sea surface applications

A new method is presented for determining the atmospheric optical thickness, aerosol scattering function, and surface albedo using measurements of the upward radiance at different view angles. It is applicable over the surface with reflectance not exceeding /spl ap/10%. The suggested approach is based on forming the data bank of aerosol scattering functions, complete enough in a sense of describing the real diversity of atmospheric phase functions both over sea and land. A performed sensitivity study shows that the error of determining the optical thickness does not exceed 10-15%. Aerosol absorption and anisotropy of the surface in typical conditions can induce additional errors up to 10 and 15%. Over the surface of Lambertian type, albedo is retrieved with an error less than 0.01, whereas over the anisotropic surface, it turns out to be close to the product of the hemispheric surface albedo and a factor of surface anisotropy. For the typical viewing geometry, characterized by fixed azimuth and varying zenith view angle, this method gives the best choice of scattering function from the data bank in a sense of proximity of its shape and anisotropy factor to those of the true atmospheric scattering function. Experimental applications of the method to the multiangle data of spectrometer MKS-M2, collected over the Caspian Sea, shows its utility in the remote sensing of atmospheric aerosol and surface albedo.