Comparative analysis of FY-4A/4B hourly quantitative precipitation estimation and surface precipitation by rain gauge during the 2023 Meiyu period in Hubei province

To compare the inversion accuracy of FY-4A and FY-4B hourly quantitative precipitation estimation (QPE), this study analyzes the recognition performance, and inversion accuracy, as well as the spatial distribution differences of FY-4A/4B hourly QPE for surface precipitation during the Meiyu process of 2023 in Hubei province. The hourly precipitation data measured by rain gauges are used as the benchmark. The results are as follows. (1) The probability of detection (POD), miss alarm rate (MAR), and false alarm rate (FAR) of FY-4A (FY-4B) hourly QPE for ground precipitation is 52% (58%), 48% (42%), and 52% (53%), respectively, indicating slightly better recognition performance of hourly QPE for FY-4B than FY-4A. (2) The correlation coefficient between the hourly QPE of FY-4A (FY-4B) and surface precipitation is 0.44 (0.44), with a mean error (ME) and root mean square error (RMSE) of 0.88 mm (0.57 mm) and 6.09 mm (5.91 mm), respectively. Overall, the hourly QPE of FY-4A/4B overestimates surface precipitation, and the inversion accuracy of FY-4B is slightly higher than that of FY-4A. Moreover, the inversion accuracy of hourly QPE of FY-4A /4B shows diurnal variations with higher accuracy during the day and lower accuracy at night, which may be related to the amount of precipitation, the frequency of rainstorms, and heavy rain. (3) For different grades of precipitation, FY-4A/4B hourly QPE overestimates light and moderate rains, yet underestimates heavy rain and rainstorms. The degree of overestimation decreases with the increase in rainfall intensity, while the underestimation increases with rain intensity. (4) The method of confining precipitation ≥20 mm to 20 mm in FY-4A/4B hourly QPE has a certain impact on its inversion accuracy. Additionally, there are spatial differences in the recognition performance and inversion accuracy of FY-4A/4B hourly QPE for surface precipitation, which may be related to the parallax difference caused by the different sub-satellite points of FY-4A and FY-4B and different radiation received by the satellites.