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2023年湖北梅雨期FY-4A/4B小时QPE与地面观测降水的对比分析

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

  • 摘要: 为对比分析FY-4A/4B小时QPE的反演精度,针对2023年湖北省梅雨过程,以地面气象站实测小时降水资料为标准,分析了FY-4A/4B小时QPE对地面观测降水的判识性能和反演精度及其空间分布差异。结果表明:(1) FY-4A (FY-4B)小时QPE对地面观测降水的命中率、漏报率、空报率分别为52% (58%)、48% (42%)、52% (53%),FY-4B小时QPE对地面观测降水的判识性能略优于FY-4A。 (2) FY-4A (FY-4B)小时QPE与地面观测降水的相关系数为0.44 (0.44),偏差和均方根误差分别为0.88 mm (0.57 mm)和6.09 mm (5.91 mm),总体上FY-4A/4B小时QPE高估了地面观测降水,而FY-4B的反演精度略高于FY-4A;FY-4A/4B小时QPE的反演精度具有白天高、夜间低的日变化特征,可能与降水量、暴雨和大雨频次有关。(3) 对不同等级降水而言,FY-4A/4B小时QPE会高估小雨和中雨,低估大雨和暴雨,其中高估程度随雨强增大而降低,低估程度随雨强增大而增加。(4) FY-4A/4B小时QPE将≥20 mm降水量处理为20 mm的方式会对其反演精度产生一定影响;FY-4A/4B小时QPE对地面观测降水的判识性能和反演精度具有空间差异,这可能与FY-4A/4B的卫星定点经度不同导致的视差差异和卫星接收的辐射差异有关。

     

    Abstract: 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.

     

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