Radiative Properties of Deformed Hydrometeors for Commonly Used Passive Microwave Frequencies

Christian D. Kummerow and James A. Weinman

ABSTRACT

Scattering parameters for ensembles of aspherical ice and liquid hydrometeors were calculated at an incidence angle of  Ψ = 50° for frequencies of 10.7, 18.0, 37.0, 50.3, and 85.6 GHz. Hydrometeors are assumed to be oblate spheroids whose semi‑minor axes are aligned with Ψ = 0°. The angle of Ψ = 50° is determined by the viewing angle of satellite‑borne radiometers. The backscattering extinction coefficients at Ψ = 0° were also calculated at 18, 37, and 85.6 GHz to provide information for future nadir scanning satellite borne radars. The hydrometeors are assumed to be characterized by Marshall‑Palmer drop size distributions. The Extended Boundary Condition Method (EBCM) is used to calculate the extinction and backscattering coefficients as well as the albedo for single scattering and the asymmetry factor of the phase function. Results are fitted to simple functions of the rainfall rate. Some comparisons intended to illustrate the differences and similarities of these results with those obtained from equal volume spheres are also presented.