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Evaluating the accuracy of MSWEP V2.1 and its performance for drought monitoring over mainland China

Xu, Zhengguang, Wu, Zhiyong, He, Hai, Wu, Xiaotao, Zhou, Jianhong, Zhang, Yuliang, Guo, Xiao
Atmospheric research 2019 v.226 pp. 17-31
case studies, climate models, drought, hydrology, monitoring, rain, rain gauges, satellites, semiarid zones, China
Long-term, reliable quantitative precipitation estimate products provide an ideal data source for large-scale drought monitoring and other related hydrological and meteorological applications. The foremost purpose of this study was to evaluate the suitability of Multi-Source Weighted-Ensemble Precipitation Version 2.1 (MSWEP V2.1) for drought monitoring over mainland China. The accuracy of MSWEP V2.1 was first evaluated against observed precipitation data derived from 586 meteorological stations. The Standardized Precipitation Index (SPI) based on MSWEP V2.1 was then validated and analyzed at multiple spatial (regional and grid) and temporal (1, 3, 6, and 12 months) scales. Finally, we considered three typical drought events as case studies and analyzed the potential of MSWEP V2.1 in capturing the temporal and spatial variations of drought conditions. The results indicated that there was good agreement between MSWEP V2.1 and the rain gauge observations, even though MSWEP V2.1 generally underestimated the precipitation over most parts of mainland China. MSWEP V2.1 exhibited the highest correlation coefficient (CC) with in situ observations at monthly timescales, followed by those at yearly timescales and daily timescales with an average CC of 0.93, 0.86, and 0.77, respectively. The MSWEP V2.1-based SPI matched well with that calculated from the precipitation data derived from the meteorological stations at multiple spatial and temporal scales. Generally, the performance of MSWEP V2.1 over eastern China was significantly superior to its performance in western China. Despite this, MSWEP V2.1 still provided a greater potential for drought monitoring over western China than two satellite-based precipitation estimates, namely the Tropical Rainfall Measuring Mission (TRMM) Multi-Satellite Precipitation Analysis (TMPA) 3B42V7 and the Climate Prediction Center morphing technique (CMORPH) satellite-gauge merged product (CMORPH BLD). Through the analysis of three typical drought events, we found that the MSWEP V2.1-based SPI could not only precisely describe the occurrence and development of drought events, but also reasonably reflect important characteristics of typical drought events, such as intensity and areal extent. In general, MSWEP V2.1 could be used as an alternative data source for drought monitoring over mainland China, particularly in eastern China. However, the performance of MSWEP V2.1 in the arid and semi-arid areas of western China still requires improvement.