Light scattering by randomly oriented spheroidal particles

Abstract

Light scattering properties of an assembly of randomly oriented, identical spheroidal particles are studied. A computation scheme has been developed to integrate the solution of Asano and Yamamoto for scattering from a homogeneous spheroid over all the particle orientations. The extinction and scattering cross sections, asymmetry factor, and scattering matrix elements are calculated for randomly oriented prolate and oblate spheroids and compared with both calculations for spheres and laboratory measurements, The scattering cross section, single scattering albedo, and asymmetry factor of spheroids tend to be larger than those for spheres of the same volume. The normalized scattering matrix has a symmetrical form with six independent elements. The angular scattering behavior of spheroids is found to be greatly different from that of spheres for side scattering to backscattering directions. In general, prolate and oblate spheroids of the same shape parameter have similar angular scattering patterns. The angular distribution of scattered intensity is characterized by strong forward scattering and weak backscattering. The linear polarization tends to be positive at intermediate scattering angles. The linear polarization and depolarization are discussed in application to scattering in the earth and planetary atmospheres.