Computation of a single-scattering matrix for nonspherical particles randomly or horizontally oriented in space

The computation of the scattering properties of cirrus cloud ice crystals b y the ray-tracing approach is described. A light beam is represented by its Stokes quadrivector I, which describes intensity as well as polarization, and the scattering properties of particles (molecules, droplets, or ice cry stals) are introduced by means of a 4 X 4 transformation matrix M known as the Mueller matrix, or M matrix. Obtaining such a matrix for each kind of p article gives access to a complete description of the scattering medium. Mo st computations of the M matrices of cirrus ice crystals have introduced se veral simplifying hypotheses, by using basic shapes, by assuming a random o rientation of the particles, or both. The present study focuses on the calc ulation of the complete M matrix for a specific shape of particles (i.e., h exagonally based crystals) either with optional oscillation about the horiz ontal plane or with random orientation. The validity of the computation cod e is checked against specific well-known cases for randomly oriented partic les. For horizontally oscillating particles the computation of this matrix is anew result. Sensitivity of the M matrix to the following variables is s tudied: refractive index, amplitude of oscillation, particle shape and size , and angle of incidence. (C) 2001 Optical Society of America.