Comparative verification and evaluation of two dual-polarization radar quantitative precipitation estimation algorithms

Abstract

[Objective] The CSU-HIDRO and WSR88D algorithms are the primary dual-polarization radar quantitative precipitation estimation(QPE) algorithms used in operational meteorology. However, their applicability varies under different climatic conditions, necessitating a detailed evaluation of the suitability of these two algorithms in the peri-Shanghai region.[Methods] Data from the S-band dual-polarization radar in Qingpu, Shanghai, and minute-level rainfall data from automatic stations within the radar coverage were utilized. Based on 46 typical precipitation events in the peri-Shanghai region from 2023 to 2024, the CSU-HIDRO and WSR88D algorithms were evaluated and verified using four method: non-stratified assessment, stratification by observed rainfall intensity(rain rate stratification), stratification by station-to-radar distance(distance stratification), and classification of influencing weather systems.[Results] The result showed that:(1) the accuracy of the CSU-HIDRO algorithm was higher than that of the WSR88D algorithm in unstratified, rain rate-stratified, and distance-stratified evaluation. Moreover, the CSU-HIDRO algorithm achieved the best precipitation estimation performance within the range of hourly rainfall intensity between 35 and 50 mm and within distances of 10 to 75 km from the radar.(2) Verification based on weather system types revealed that both algorithms demonstrated comparable precipitation estimation performance for weather systems forced by upper-level cold advection. However, for samples of weather systems forced by low-level warm advection, quasi-barotropic systems, and baroclinic frontogenesis systems, the CSU-HIDRO algorithm outperformed the WSR88D algorithm in quantitative precipitation estimation.[Conclusion] Overall, the CSU-HIDRO algorithm demonstrates stronger applicability in the peri-Shanghai region. It provides higher estimation accuracy, especially for moderate rainfall intensity and medium distances, thereby providing a better option for radar-based precipitation retrieval in this region.

Keywords

dual-polarization radar / WSR88D / CSU-HIDRO / precipitation estimation / verification and evaluation / minute-scale rainfall / weather pattern classification / influencing factors