Radar reflectivity in snowfall

Backscattering properties of dry snowflakes at different microwave frequencies are examined. It is shown that the Rayleigh approximation does not often provide the necessary accuracy for snowflake reflectivity calculations for radar wavelengths used in meteorology; however, another simple approximation, the Rayleigh-Gans approximation, can be safely used for such calculations. Reflectivity-snowfall rate relationships are derived for different snow densities and different radar frequencies. It is shown that dual-wavelength radar measurements can be used for estimating the effective sizes of snowflakes. Experimental data obtained during radar snowfall measurements in the WISP project of 1991 with the NOAA X- and Ka-band radars are found to be consistent with the described theoretical results