Abstract:
Quantitative precipitation estimation (QPE) products derived from weather radar have the advantages of wide spatial coverage and high temporal resolution. Accurate and reliable QPE is crucial for precipitation monitoring and forecasting as well as disaster warning. Based on the data from the dual-polarization weather radar at Jingzhou station and hourly precipitation of rain gauge at national automatic weather stations (AWSs) in the Jianghan Plain during the 2023 Meiyu period, the identification performance and accuracy of dual-polarization weather radar QPE including its influencing factors is analyzed. The results are as follows. (1) the hit rate of radar QPE in identifying ground precipitation is 74.7%, the false alarm rate is 28%, and the critical success index is 57.9%. The radar QPE performs well in identifying heavy storm rain, followed by moderate rain, yet its ability to depict heavy and light rains needs to be improved. (2) The radar QPE and rain gauge have good consistency in measuring hourly precipitation, with a correlation coefficient (CORR) of 0.91, a mean error (ME) of -0.27 mm, a relative mean error (RME) of -13%, and a root mean square error (RMSE) of 1.96 mm. As a whole, the radar QPE underestimates ground precipitation. The ME and RMSE of hourly precipitation between radar QPE and rain gauge increase with increasing rainfall intensity, but the CORR between them is higher in heavy storm rain than in other grades of precipitation. (3) Radar beam blockage can lead to underestimation of radar reflectivity, which in turn reduces the performance of the quantitative precipitation estimation algorithm in detecting surface precipitation, with the identifying performance in some areas decreasing by about 20%. Additionally, the radar QPE accuracy is relatively less affected by the sampling height of the reflectivity factor, and the
ME of hourly precipitation between radar QPE and rain gauge presents little change with varying sampling height. However, as the sampling height increases, the dispersion and outliers of radar QPE fluctuate greatly, making it easy to underestimate ground precipitation.