Evaluation of Polarimetric Radar-Based Precipitation Estimates in Southern China

Compared to traditional single-polarization weather radar, dual-polarization radar can get more useful information about hydrometeor type and size distribution through additional polarimetric measurements. The polarimetric radar also has better performance in detecting and quantifying precipitation rate and amount. This paper implements a dual-polarization radar rainfall algorithm for the polarimetric radar systems in Southern China. The quality control of dual-polarization radar measurements in China is also detailed. The rainfall system is driven by a region-based hydrometeor classification mechanism, which incorporates the spatial coherence and self-aggregation of various polarimetric observables. In addition, local raindrop size distribution (DSD) data are used to derive the localized radar rainfall relations. For demonstration purposes, data collected by the S-band dual-polarization radar deployed in Yangjiang, Guangdong during a few heavy rain cases are investigated, including July 23, August 23, and October 15, 2017 events. In addition, this paper also compares the localized rainfall relations with various commonly used rainfall relations such as those used by WSR-88D radar. Results show that the rainfall estimates with localized polarimetric algorithms agree better with rainfall observations from ground disdrometers and rain gauges.