Orientation probability densities of ice crystals constituting cirrus clouds are required for correct interpretation of the lidar signals. It is shown that in the case of the azimuthal orientation, the probability density function can be constructed as a superposition of azimuthal and zenith distribution functions. However, such a superposition has a discontinuity in the poles of the orientation unit sphere, so it would be preferable to use Fisher or Kent distributions. The backscattering Mueller matrix has been calculated for the hexagonal ice columns and plates for the first time. Possibility of retrieving the orientation distributions of the crystals from a vertically pointing polarization lidar measuring the full Mueller matrix is considered. It is shown that for the columns the element m₄₄ or, equivalently, the circular depolarization ratio distinguishes between the low and high zenith tilts of the crystals. Then, at their low or high zenith tilts, off-diagonal elements should be measured to retrieve the azimuth tilts.

Date Published: 29 November 2016
PDF: 9 pages
Proc. SPIE 10035, 22nd International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics, 100353L (29 November 2016); doi: 10.1117/12.2248735

Published in SPIE Proceedings Vol. 10035:
22nd International Symposium on Atmospheric and Ocean Optics: Atmospheric Physics
Gennadii G. Matvienko; Oleg A. Romanovskii, Editor(s)