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(Z_H), R(Z_H, Z_DR) and R(K_DP), 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(Z_H) approach performs better for the precipitation rate less than 5 mm h^-1, and R(K_DP) is better for the rate higher than 5 mm h ^-1, while R(Z_H, Z_DR) has the worst performance.An adaptive approach is developed by taking the advantages of both R(Z_H) and R(K_DP) approaches to improve the QPE accuracy.