Utilization of Specific Attenuation for Radar Quantitative Precipitation Estimation in Southern China

The improvement of dual-polarization radars brings opportunities and challenges to radar quantitative precipitation estimation (QPE). During the last two decades, various combinations of reflectivity Z, differential reflectivity Z_DR and specific differential phase K_DP are exploited in the field of QPE algorithms. However, it found that although these methods provide robust QPE in a wide range of rain intensity, their performance heavily depend on the data quality, drop size distribution (DSD) variation and so on. A novel rainfall retrieval using specific attenuation A put forward by Ryzhkov theoretically showed that the R(A) relation relies less on DSD than traditional rainfall algorithms. What’s more, the R(A) method is also immune to the radar miscalibration biases, partial beam blockage and wet radome. According to this approach, the attenuation is estimated with the ZPHI method computed from Z and the path-integrated attenuation (PIA). In this study, the R(A) method is utilized in the QPE algorithm using the S-band dual-polarization radar in southern China where the lowest antenna tilt sometimes heavily blocked by the mountains and high buildings and extreme precipitation happens frequently. The R(A) scheme is tested for different weather conditions including convective, stratiform and typhoon precipitation systems.