Numerical CPR Simulation of Polarimetric Echoes from Moon Cratered Surface for Analysis of Mini-RF Data

Circular polarization ratio (CPR) was regarded as an important index for water ice existence in permanently shadowed region (PSR) of the Moon poles. However, some studies have intuitively described that the double bounce scattering caused by dihedral structure of stone facets may yield high CPR as well. In this paper, a numerical model of the Moon cratered rough surface with volumetric scatterers, e.g. rock-stones, is developed. The bidirectional analytic ray tracing (BART) method is applied to numerically solve high-order scattering of lunar rough surface and volumetric rock-stones. The lunar surface is modeled by Digital Elevation Model (DEM) data from Lunar Reconnaissance Orbiter (LRO) Lunar Orbiter Laser Altimeter (LOLA). It is the first numerical approach to quantitatively analyze how the cratered surface topography, discrete stones and radar local incidence etc. affect and enhance the CPR.