Extinction cross sections and albedos for particles with very rough surfaces

Abstract

Using the full wave approach, the scattering cross sections for finitely conducting particles with very rough surfaces are expressed as weighted sums of specular point (physical optics) and diffuse scattering cross sections. Through judicious use of the forward-scattering theorem and the observation that for large particles the forward-scattered “shadow forming wave is the same for all surfaces which have the same shadow line,” the albedos and the extinction cross sections for particles with rough surfaces are evaluated. These computations are essential to solve the equation of radiative transfer for the specific intensities (Stokes parameters) in media consisting of random distributions of particles with rough surfaces. The particle surface roughness has a significant effect on the diffuse specific intensities.