Drop Size Distribution Retrievals for Light Rain and Drizzle from S-Band Polarimetric Radars

Measurements of full drop size distribution (DSD) spectra were used as input for scattering calculations to derive fitted equations for light rain and drizzle for estimating the mass-weighted mean diameter, Dm, from radar reflectivity (Zh) at S-band. Testing was performed using Zh measured S-band polarimetric radars over two different disdrometer locations versus Dm from disdrometer measurements. Consistent results were obtained but only for Zh < 18 dBZ for light rain and <5 dBZ for drizzle. Additionally, gridded radar data were used to identify light rain and drizzle regions, and their Dm histograms were compared with those derived from stratiform and convective rain regions.