Aerosol optical parameters retrieved from ground measurements of scattered solar radiation in Kazakhstan

摘要

Abstract: For atmospheric correction of satellite signals in optical channels, aerosol spectral optical depth and phase functions have to be known. These aerosol parameters have been retrieved from ground measurements of direct and diffuse solar radiation in South-Eastern Kazakhstan. Field experiments were conducted in 1996 - 1998 years during July - September. Only cloud-free days with the stability of atmospheric optical transparency during 2 and more hours of measurements were taken for data processing and analysis. The algorithm for retrieval of aerosol phase function is based on numerical calculations of multiple scattering in the plane-parallel atmosphere with the Lambertian surface by modified method of spherical harmonics. It provides angular values of aerosol phase function within 10 - 35% of error, depending on the wavelength and scattering angle. It is shown that aerosol optical parameters in Kazakhstan are significantly differ from other global and regional aerosol models by both spectral dependence and range of absolute values. The anomal spectral behavior of aerosol optical depth (with the maximum around 0.45 micrometer) was registered in about 50% of cases for clean atmosphere. !10