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

Quantitative precipitation estimation (QPE) is one of the important applications of dual-polarization radar. Four commonly used QPE methods include R(Z_H) based on reflectivity (Z_H), R(Z_H, Z_DR) based on Z_H and differential reflectivity (Z_DR), R(K_dp) based on specific differential phase (K_dp), and R(K_dp, Z_DR) based on K_dp and Z_DR. 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 K_dp can improve the precipitation estimation of the X-band radar. Compared with R(Z_H) and R(Z_H, Z_DR), the precipitation estimation of R(K_dp) and R(K_dp, Z_DR) is significantly improved. Among the four methods and X-QPE, R(K_dp, Z_DR) performs best in both accuracy and stability. (2) For the estimation by R(K_dp, Z_DR), 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(Z_H). However, for rainstorms, convective precipitation, and deep convection precipitation, the performance of R(K_dp, Z_DR) on precipitation estimation is significantly improved.