Microphysical characteristics of the 2020 record-breaking Meiyu rainfall in Anhui, China

The 2020 Meiyu season in Anhui, China, brought unprecedented rainfall, driven by a unique interplay of high precipitation frequency and elevated convective rainfall. This study examines the distinctive microphysical characteristics of raindrop size distribution (DSD) during this record-breaking season, using minute-level data from six disdrometer stations. Brief but intense rain events contributed up to 49.4 % of the total seasonal rainfall in only 6–7 % of the duration, with the mean drop diameter increasing from 1.2 mm to 2.1 mm and the mean normalized intercept parameter rising from 2.7 to 4.1 as rainfall rate intensified. Compared to prior Meiyu studies, our findings reveal distinct DSD patterns with larger raindrops and higher concentrations, reflecting a more convective-dominated structure unique to the 2020 season. Novel μ–Λ and Z − R relationships tailored for this event revealed larger raindrop sizes and concentrations compared to past studies. Enhanced dual-polarization radar rainfall prediction models were developed, with relationships between Zdr, Zh, Kdp, and rainfall rate (R) showing exceptional accuracy, as evidenced by correlation coefficients nearing 1.0 and low RMSE and NMAE values. Additionally, new KE–R relationships accurately estimated rainfall kinetic energy (KE), with Power Law models best representing KEtime–R and Logarithmic fits for KEmm–R. These findings demonstrate the importance of DSD-specific insights for understanding microphysical processes and improving QPE accuracy, with implications for flood and soil erosion management in eastern China.