Calculation by the Monte-Carlo method of optical radiation scattering by cirrus crystals in the geometric optics approximation

In the geometrical optics approximation, the scattering of solar radiation in the visible and near-IR regions of the solar spectrum by particles of crystalline clouds is numerically studied. For this purpose an algorithm for direct statistical simulation has been developed. A feature of the algorithm is the ability to obtain the scattering characteristics of solar radiation by crystalline particles of various shapes, concentrations and spatial orientations in a single calculation. Another feature is that, along with particles having smooth surfaces, the processes of radiation scattering on particles with rough surfaces are simulated taking into account the effects of shading and re-reflection. The algorithm is based on the so-called "facet" model of randomly inhomogeneous surfaces. A series of numerical experiments has been performed.