An aircraft lidar method of studying aerosol in the free troposphere over Siberia

This paper reports on the results of aircraft lidar studies of aerosol in the free troposphere in the Arctic and middle latitudes of Siberia in the summer of 1993. In the course of these studies, measurements were made of aerosol scattering and depolarization coefficients which characterize its optical thickness and phase state, as well as aerosol spatial distribution. Through analyzing the results obtained it has been established that tropospheric aerosol has a fine-cell and stratified structure. Its volume scattering and depolarization coefficients are within the limits of σ = (0.88−84) × 10−5 m−1 and δ = 0.01−0.15, respectively. The values of these parameters largely depend on atmospheric pollution, the geographical position of measurement sites in relation to industrial regions, and weather situation, particularly, air parcels transport direction and temperature distribution. In sub-inversion layers, and values are considerably higher than in the adjacent ones. The mean values of the scattering and depolarization coefficients obtained in these studies differ but insignificantly from those obtained in the same regions by other researchers.