Assessment of three gridded satellite-based precipitation products and their performance variabilities during typhoons over Zhejiang, southeastern China

Abstract

• IMERG-Early, GSMaP-NRT and FY4A QPE were evaluated for overall performance and five typhoons during 2018–2019. • IMERG-Early and GSMaP-NRT performed much better than FY4A QPE. • Satellite-based products tended to underestimate heavy precipitation but overestimate light precipitation. • Satellite-based products showed unstable performance and were more likely to present low estimations during typhoons. • Satellite-based products were difficult to detect heavy precipitation centers during typhoons in some parts of southwestern Zhejiang with complex topography. Effective and accurate estimation of heavy precipitation from typhoons is critical for the early warning of hydrological extremes and disaster mitigation. Satellite-based precipitation products are widely used for various purposes, including supporting climate, hydrology, and severe weather event monitoring and research activities. In this study, the performance of Integrated Multi-SatellitE Retrievals for Global Precipitation Measurement (IMERG), Global Satellite Mapping of Precipitation (GSMaP), and Chinese Fengyun-4A quantitative precipitation estimates (FY4A QPE) were compared to daily observations from 2018 to 2019. Further comparison of these products at an hourly scale was implemented for five typhoons that made landfall in the coastal areas of southeastern China. The results demonstrate that IMERG-Early and GSMaP-NRT performed much better than FY4A QPE, in both overall assessment and specific typhoons. All the satellite-based products showed the best correlations with the gauge observations for heavy precipitation events, and their correlations became worse with lower precipitation intensity. They tended to underestimate heavy precipitation but overestimate light precipitation. Furthermore, their random errors increased with increasing precipitation, according to an analysis of unbiased root mean squared error (ubRMSE). Based upon analyses of the probability of detection (POD) and critical success index (CSI), satellite-based products performed better during light precipitation events than moderate and heavy precipitation events. During typhoons, IMERG-Early and GSMaP-NRT had better accuracy in detecting typhoon precipitation with higher POD and CSI values. FY4A QPE showed instability in different typhoons and a low correlation with gauge observations. In addition, satellite-based products produced precipitation estimates more reliably in northern and eastern Zhejiang, but were difficult to detect heavy precipitation centers in some parts of southwestern Zhejiang with complex topography. These findings not only provide valuable references for the development of satellite-based retrieval algorithms to enhance the ability to monitor typhoon heavy precipitation but also support diverse hydrological models and applications.