SPEI and multi-threshold run theory based drought analysis using multi-source products in China

With the accelerated climate change, the selection of globe-warming related drought monitoring tools is vitally significant. To select the most suitable multi-source precipitation product for drought monitoring, this study comprehensively evaluated the performance of 7 latest version of multi-source precipitation estimate products (MPEs, including PERSIANN-CDR, CHIRPS, ERA5, MERRA2, APHRODITE, GPCC and MSWEP) and compared their drought monitoring applicability combined with GLEAM potential evapotranspiration (ETP) product based on the standardized precipitation evapotranspiration index (SPEI) during 1983-2015 over China. The SPEI estimated by the China monthly Precipitation Analysis Product (CPAP) was used as the reference to assess their performance. In addition, the drought area ratio, frequency, duration and intensity were analyzed based on the multi-threshold run theory. The results showed that: (1) The precision of MPEs was higher in eastern China but lower in western China, and the overall accuracy of MPEs summarized as 4 levels from top to end respectively was GPCC and APHRODITE, MERRA2 and MSWEP, CHIRPS and PERSIANN-CDR as well as ERA5. GLEAM ETP performed well in eastern China but poor in western China with large underestimations. (2) The applicability of MPEs in drought monitoring was regional-specific (low in parts of Northwest Desert and Qinghai-Tibet Plateau, but high in other areas). The accuracy of estimated SPEI for most MPEs dropped with expanding timescale in most sub-regions. Among of MPEs, GPCC product comprehensively performed best in drought monitoring. (3) Drought events occurring in northern China were usually with larger area ratio, lower frequency and longer duration than other regions. Drought events had an exacerbating trend in southeastern China. Overall, this study provides significant information to choose suitable datasets for globe-warming related drought studies.