Earth and Space Science (Jan 2021)
Seasonal Error Component Analysis of the GPM IMERG Version 05 Precipitation Estimations Over Sichuan Basin of China
Abstract
Abstract An error decomposition method is used to analyze and track seasonal error sources of the Integrated Multi‐satellitE Retrievals for the Global Precipitation Measurement (IMERG) Version 05 daily precipitation estimations, including Early‐, Late‐, and Final‐run products (IMERG‐DE, IMERG‐DL, and IMERG‐DF, respectively) over the Sichuan Basin of China from January 2016 to December 2018. The method decomposes the total errors into hit bias, missed precipitation, and false precipitation, which can be attributed to the satellite retrieval processes. Results show that in spring, all the estimations had serious overestimation in the northwest of the basin. The major error source is the hit bias of the intensity over 25 mm/day. In summer, the three IMERG estimations overestimated the precipitation in almost the entire Sichuan Basin, especially in the south and southwest. The principal determinants of the error sources are missed and false light precipitation (<25 mm/day), while hit bias and false precipitation are the leading error sources for the moderate precipitation (25–54 mm/day). In autumn, the IMERG‐DF's overestimation mainly comes from hit and false moderate precipitation (15–64 mm/day), while the underestimation of the IMERG‐DE and DL is mainly determined by missed and false precipitation of the precipitation less than 15 mm/day. In winter, the main contributors to the underestimation of the IMERG‐DE and DL estimations are missed and false lighter precipitation (<8 mm/day). However, the total errors of the IMERG‐DF are resulting from the three components canceling one another. Additionally, missed precipitation often takes place in the autumn and winter and false precipitation in summer and winter. The IMERG‐DL shows better error control of positive hit bias and false precipitation than do the other estimations in summer.
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