Improvements and limitations of the latest version 8 of GSMaP compared with its former version 7 and IMERG V06 at multiple spatio-temporal scales in mainland China

Abstract

The latest version of the Global Satellite Mapping of Precipitation (GSMaP Version 8), released in December 2021, necessitates a thorough evaluation of its merits and drawbacks relative to other satellite precipitation products in the Global Precipitation Measurement (GPM) era. A comprehensive assessment is crucial for both end-users and algorithm developers. This study performs a multi-scale evaluation and comparison of daily and hourly precipitation from GSMaP V8, GSMaP V7, and the Integrated Multi-satellite Retrievals for GPM (IMERG) V06 across mainland China and eight climatic regions. The evaluation encompasses four aspects: detection of rain/no-rain events, quantification of precipitation amount, capturing diurnal cycle features, and monitoring extreme events. The results indicate that: (1) GSMaP V8 excels in distinguishing rain/no-rain events on both daily and hourly scales during summer and accurately quantifying winter precipitation, surpassing the performance of GSMaP V7 and IMERG V06. (2) Regarding the diurnal cycle feature, GSMaP V8 outperforms V7 in the eastern Qinghai-Tibetan Plateau (TP) and the southern part of northeastern China and exceeds IMERG V06 in northeastern and northern China. (3) Compared with IMERG V06, GSMaP V8 demonstrates superior agreement with gauge observations in monitoring extreme precipitation and drought events in 2022 and 2023. (4) Limitations of GSMaP V8 include a reduced capacity to accurately estimate hourly and daily precipitation over northeastern and northern China in summer compared to GSMaP V7. Additionally, it exhibits lower accuracy in estimating precipitation amounts over TP than IMERG V06. This study provides an initial assessment of GSMaP V8, highlighting insights into its strengths and weaknesses that are pivotal for choosing and utilizing satellite precipitation products in hydrometeorological applications during the GPM era.