Precipitation Particle Size Distributions Characterized by Video Disdrometer and Polarimetric Radar Measurements

Accurate quantitative precipitation estimation and forecast require the characterization of precipitation microphysics, including precipitation particle size distribution (PSD). Precipitation (rain or snow) PSDs can be measured by disdrometers or retrieved from polarimetric radar observations. A two-dimensional video disdrometer (2DVD) measures the size, shape, orientation and falling speed of each precipitating particle, and hence PSDs that allow for the calculations of polarimetric radar variables. Multi-parameter polarimetric radar measurements allow for the retrieval of raindrop size distributions (DSDs) and snow PSDs, yielding 3D spatial distribution and temporal evolution of PSDs. In this paper, we present data from and analysis for 2DVD and S-band polarimetric radar observations made of a few rain/snow events that occured in central Oklahoma. Rain DSDs and snow PSDs are retrieved from the PRD to study precipitation microphysics. Cases studied include an isolated convective storm, a squalline case and winter storms. Radar-disdrometer comparisons show that PRD-retrieved PSDs are accurate and reliable and allow storm structure and evolution of microphysics be characterized.