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 w ere made of aerosol scattering and depolarization coefficients which c haracterize its optical thickness and phase state, as well as aerosol spatial distribution. Through analyzing the results obtained it has be en established that tropospheric aerosol has a fine-cell and stratifie d structure. Its volume scattering and depolarization coefficients are within the limits of sigma = (0.8-8.4) x 10(-5) m(-1) and delta = 0.0 1-0.15, 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, particularl y, air parcels transport direction and temperature distribution. In su b-inversion layers, and values are considerably higher than in the adj acent ones. The mean values of the scattering and depolarization coeff icients obtained in these studies differ but insignificantly from thos e obtained in the same regions by other researchers. (C) 1997 Elsevier Science B.V.