Abstract :
In general, it is very difficult to explain all of the polarimetric radar measurables in winter precipitation simultaneously using spheroidal shape models with specified densities and orientation distributions. In fact, even for Rayleigh scattering, where the spherical or spheroidal shape assumption is reasonable for reflectivity computation, it is not sufficient for computing the full scattering matrix and related radar measurables, required for radar-based particle classification. So, even at the S-band (all WSR-88D radars), some radar observables significantly depend on the shape and composition of particles, and sophisticated computational electromagnetics (CEM) methods are needed for scattering computations. With the advent of optical imaging disdrometers that can measure fall speed along with projected particle views in two planes, we can reconstruct more realistic 3D shapes of hydrometeors when compared to spheroidal approximations.
