Application of X-band Polarimetric Phased-array Radars in Quantitative Precipitation Estimation

The performance of different quantitative precipitation estimation (QPE) relationships is examined using the polarimetric variables from the X-band polarimetric phased-array radars in Guangzhou, China. Three QPE approaches, namely, R(ZH), R(ZH, ZDR) and R(KDP), are developed for horizontal reflectivity, differential reflectivity and specific phase shift rate, respectively. The estimation parameters are determined by fitting the relationships to the observed radar variables using the T-matrix method. The QPE relationships were examined using the data of four heavy precipitation events in southern China. The examination shows that the R(ZH) approach performs better for the precipitation rate less than 5 mm h-1, and R(KDP) is better for the rate higher than 5 mm h-1, while R(ZH, ZDR) has the worst performance. An adaptive approach is developed by taking the advantages of both R(ZH) and R(KDP) approaches to improve the QPE accuracy.