Microwave brightness temperatures from precipitating cloud with water-coated ice spheres

The effects of the hydrometeor spectra and water-coated ice spheres in a precipitating cloud on radiation transfer has been studied in a numerical experiment with an algorithm for analytical solution to microwave radiance based on the Eddington approximation. The results have shown that radiant fluxes at some levels in the cloud would change if either the size spectrum changes or some of the ice spheres are coated with liquid water. Nevertheless, whether the variation can be reflected in out-going brightness temperatures at the earth's surface and cloud top depends on rainfall rate, wavelength, size spectrum of water-coated ice spheres, and the thickness of the coat. Radiation transfer and out-going brightness temperatures at 6.6, 10.7 and 18 GHz are influenced more than at higher frequencies.