Effective permittivity of and scattering from wet snow and ice droplets at weather radar wavelengths

In this parametric study, wet snow and ice droplets are modeled as sparse collections of Rayleigh scatterers (size small compared to wavelength) consisting either of ice or of composite mixtures of air and ice in water. An effective permittivity is calculated using various extended Maxwell-Garnett-type models to account for variations in shape and orientation of the constituents. The backscatter radar cross section is calculated as an incoherent sum of individual particle cross sections, and for various distributions of shape, size, and orientation. The results indicate a dependence of the radar cross section on the polarizations of the incident and reflected fields. This dependence is shown in the differential reflectivity, defined in terms of the ratio of the backscatter cross sections due to two mutually orthogonal linearly polarized incident electric fields.< >