BENCHMARK RESULTS FOR SINGLE SCATTERING BY SPHEROIDS

The light scattering properties of aerosol particles are often described using Mueller matrices and the Stokes formalism. The Stokes parameters of the incident light are then transformed into those of the scattered light by means of a scattering matrix. It is often advantageous to expand the elements of the scattering matrix in generalized spherical functions, especially if the aerosol scattering properties are to be used in radiative transfer codes for calculating the polarized radiation field in a planetary atmosphere. In this paper, expansion coefficients are presented for: (i) randomly-oriented prolate spheroids with aspect ratio a/b = 4.0, size parameter x = 10.079368, and a refractive index m = 1.55 - 0.01i; (ii) randomly-oriented oblate spheroids with a/b = 1.999987, x = 3.0, and m = 1.53 - 0.006i; (iii) an ensemble of randomly-oriented prolate spheroids with a modified gamma size distribution for their semi-major axes, with a/b = 1.4 and m = 1.50 - 0.008i, representing a model for a volcanic aerosol. In addition, values for scattering and extinction efficiencies, albedos, average projected geometric cross-sections, asymmetry parameters, volumes, and scattering matrix elements (for a limited number of scattering angles) have been tabulated. The numerical results presented here have mostly been calculated with the T-matrix method and were checked in various ways. All results are expected to be accurate to six decimal places and can be used as benchmark results.