Optical and microphysical characteristics of aerosol structures in Central Asia

Abstract

Regular measurements of tropospheric aerosol parameters have been performed from January 2002 to May 2007 at Lidar Station Teplokluchenka, Kyrgyzstan (42.40° N, 78.50° E). A combined multiwavelength and Raman lidar was used to measure profiles of the aerosol backscatter and extinction coefficients, depolarization ratio and structure of the planetary boundary layer. The statistical analysis of aerosol optical properties was made both for the planetary boundary layer and for the free troposphere. Data on the aerosol backscatter profiles, which characterize a typical variation of vertical aerosol distribution, were selected for analysis. The results show seasonal values of the aerosol backscatter coefficient and the backscatter ratio in a mountainous region of Central Asia. Mean aerosol optical characteristics are estimated. Diurnal cycles of the planetary boundary layer optical characteristics are also presented. The particularities variability of optical and microphysical characteristics of the dust aerosol are revealed. The particle size distribution function and the complex refractive index have been found using the measurements of the aerosol backscattering coefficient at three wavelengths and the extinction coefficient at one wavelength. The dust events contribute significantly to very large aerosol backscatter and extinction coefficients in the boundary layer. The large masses of the dust aerosol are transported from Aral Sea basin and Middle East.