Analysis of radar quantitative precipitation estimation using X-band polarimetric radar

Abstract

Quantitative precipitation estimation (QPE) is one of the important applications of dual-polarization radar. Four commonly used QPE methods include R(ZH) based on reflectivity (ZH), R(ZH, ZDR) based on ZH and differential reflectivity (ZDR), R(Kdp) based on specific differential phase (Kdp), and R(Kdp, ZDR) based on Kdp and ZDR. With the 36-hour observation of precipitation processes during the X-band polarimetric radar networking test, the four QPE methods used by the S-band polarimetric radar are optimized to make it applicable to the X-band polarimetric radar with optimization algorithms. The performance of rainfall estimation by the optimized methods is evaluated compared to the X-band radar quantitative precipitation estimation products (X-QPE). The results show that: (1) The QPE methods with polarization parameter Kdp can improve the precipitation estimation of the X-band radar. Compared with R(ZH) and R(ZH, ZDR), the precipitation estimation of R(Kdp) and R(Kdp, ZDR) is significantly improved. Among the four methods and X-QPE, R(Kdp, ZDR) performs best in both accuracy and stability. (2) For the estimation by R(Kdp, ZDR), the results on stable and mixed precipitation is slightly worse than that of X-QPE, and the results on heavy rain are slightly worse than that of R(ZH). However, for rainstorms, convective precipitation, and deep convection precipitation, the performance of R(Kdp, ZDR) on precipitation estimation is significantly improved.