BACKWARD AND FORWARD SCATTERING BY THE MELTING LAYER COMPOSED OF SPHEROIDAL HYDROMETEORS AT 5-100 GHZ

This paper addresses the behavior of the differential reflectivity, sp ecific attenuation, and specific phase shift due to a melting layer co mposed of oblate-spheroidal hydrometeors. The results are based on a m elting layer model and scattering computations derived from the point- matching technique with the truncation and recurrence adjusted, Comput ations at 5-100 GHz for five raindrop size distributions at rain rates below 12.5 mm/h are presented. In general, the reflectivity factor an d differential reflectivity features with height at centimeter wavelen gths agree with available radar measurements. At millimeter wavelength s, contributions to the radar backscatter from smaller hydrometeors be come more and more important as the frequency increases and approaches 100 GHz. This should be instructive for utilizing millimeter waveleng th radar techniques in radar remote sensing studies of the melting lay er, Corresponding vertical profiles of the specific attenuation and ph ase shift are also presented at 5-100 GHz, The differential attenuatio n and phase shift indicate the particle shape effects, These attenuati on and phase shift become more and more considerable as the frequency increases, Such forward scattering calculations should prove useful fo r studying propagation effects caused by the melting layer for satelli te-earth communications, including depolarizations.