Comparison of various linear depolarization parameters measured by lidar

Different definitions for estimating the degree of changes in signal polari zation measured by lidar measurements are used both to detect the presence of nonspherical aerosol particles and to estimate their shape and density. Our aim is to provide a tool for calculation and interpretation of changes in polarization that are due to aerosol backscatter measured by the lidar t echnique. An overview of several techniques used to calculate linear depola rization from two-channel lidar measurements is given. Advantages and disad vantages of each method are analyzed when we apply them on a lidar vertical profile. Systematic errors are also discussed. First, an overview of diffe rent estimations of polarizability of atmospheric molecules is given. The p resence of signal with orthogonal polarization in each channel (cross talk) is a source of error in depolarization estimation. It is calculated at var ious degrees of contamination, and the total uncertainty on depolarization definition is retrieved. (C) 1999 Optical Society of America. OCIS codes: 2 80.3640, 280.1310, 290.1350.