Shape dependence of the optical properties in size-shape distributions of randomly oriented prolate spheroids, including highly elongated shapes

A sensitivity study is conducted to assess the effect of particle shape on the optical properties of size-shape distributions of randomly oriented pro late spheroidal particles. The emphasis is on covering a large range of the spheroids' aspect ratio in order to include the effects of highly aspheric al particles. A modified separation of variables method is used to compute the optical properties of an ensemble of randomly oriented particles of dif ferent sizes and shapes. The investigation shows that the elements F-11, F- 22/F-11, and F-34/F-11 of the Stokes scattering matrix are very sensitive t o a variation in the effective aspect ratio of the equiprobable shape distr ibution considered here. This implies that the effective aspect ratio will have significant impact on the radiance, the degree of linear polarization, and the degree of circular polarization of light multiply scattered by suc h an ensemble of particles. The same elements are only mildly sensitive to a variation in the effective variance of the shape distribution. The remain ing elements of the scattering matrix are moderately sensitive to a variati on in the effective aspect ratio, and rather insensitive to a variation in the effective variance. The single-scattering albedo and the asymmetry para meter are found to be near-linear functions of the effective aspect ratio a nd rather insensitive to the effective variance. The results indicate that knowledge of the effective aspect ratio might be sufficient to characterize the single-scattering albedo and the asymmetry parameter df the shape dist ribution.