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In this study, a comprehensive evaluation of the reliability of seventeen satellite-, reanalysis-, and gauge-based precipitation products (i.e., IMERG-F, GSMaP-G, TMPA 3B42, CMORPH-CRT, PERSIANN-CDR, CHIRPS, IMERG-E, IMERG-L, GSMaP-RT, TMPA-RT, PERSIANN-RT, ERA5, ERA-Interim, MERRA2, GPCC, CPC, and CRU) was conducted for drought monitoring from June 2000 to December 2019 over mainland China. The girded China monthly Precipitation Analysis Product (CPAP) with a dense station network was used as the benchmark observed precipitation data. The Standardized Precipitation Index (SPI) was used as a drought monitoring tool. The comprehensive evaluation procedures were implemented by a monthly precipitation evaluation, various timescales SPI verification, and typical drought event analysis. The results indicated that the performance of per precipitation product is in accordance with the generally higher monthly accuracy in eastern China than that in western China. The post-process satellite precipitation products, particularly bias-adjusted GPM-based products, i.e., the IMERG-F and GSMaP-G, are significantly better at detecting the monthly precipitation than the reanalysis (ERA5 and ERA-Interim), and near real-time satellite precipitation datasets. The best performances are observed for MERRA2 from reanalysis-based precipitation datasets, and GPCC from gauge-based precipitation products, for both precipitation estimation and drought monitoring. Regarding drought monitoring, the performance ranking of most precipitation products is basically consistent with monthly precipitation estimation. The SPI behaviors based on the bias-adjusted GPM-based products have inferior performance than those in MERRA2 and GPCC at the continental scale. Nevertheless, some discrepancies exist in the reliability level of drought detection in sub-regions and multi-timescales. Integrally, the IMERG-F is evaluated to be the most ideal precipitation data among the seventeen precipitation products for drought monitoring in eastern and southwest China. However, in comparison to the GPCC performance, the accuracy of satellite precipitation products should be further improved in the Xinjiang and Tibet Plateau regions. The outcomes of this study will provide valuable insights into the drought monitoring by using multi-sources open access precipitation products across mainland China. • 17 precipitation products reliability were analyzed over mainland China. • Reanalysis- and gauge-based datasets were used to reveal the performance level of satellite-estimated drought. • IMERG-F is the most suitable dataset for drought research in eastern and southwest China [ABSTRACT FROM AUTHOR]

In this paper, we comprehensively evaluated the utility of integrated long-term satellite-based precipitation and evapotranspiration products for drought monitoring over mainland China. The latest Integrated Multi-satelliteE Retrievals for Global Precipitation Measurement V06 three Runs precipitation products, i.e., the near real-time Early Run (IMERG-E) and Late Run (IMERG-L) and the post-real time Final Run (IMERG-F), and the Global Land Evaporation Amsterdam Model V3.3a (GLEAM) potential evapotranspiration (PET) products from 2001 to 2017 were considered. The accuracy of IMERG precipitation and GLEAM PET products was first evaluated against observed precipitation and Penman-Monteith method estimated PET, respectively, based on dense meteorological station network. The Standard Precipitation Evapotranspiration Index (SPEI) calculated based on IMERG precipitation and GLEAM PET products (SPEIs, including SPEI E , SPEI L and SPEI F corresponding to IMERG-E, IMERG-L and IMERG-F, respectively) were then validated by using SPEI calculated based on meteorological data (SPEIm) at multiple temporal-spatial scales. Finally, four typical drought events were selected to analyse the ability of SPEIs to characterize the temporal-spatial evolution of drought situations. The results showed that the IMERG-F presents much better performance than IMERG-E and IMERG-L in terms of higher CC and smaller BIAS and RMSE values over mainland China. The GLEAM PET well simulated the change trend of reference PET, but generally underestimated reference PET in Northwest China (NW), Xinjiang (XJ) and Qinghai–Tibet plateau (TP). In general, the performances of SPEIs over eastern China and Southwest China (SW) were significantly superior to their performances in the NW, XJ, and TP regions. Even though the SPEI F performed the best, the SPEI E and SPEI L also performed reasonably well in some specific regions. SPEIs can well capture the temporal process and reasonably reflect the spatial characteristics for four typical drought events. It is thus highlighted that the latest IMERG precipitation (especially for IMERG-F) and GLEAM PET products could be used as alternative data sources for comprehensive drought monitoring, on account of the water balance principle over mainland China, particularly in eastern China and SW China. The outcomes of this study will provide valuable references for drought monitoring by integration of multi-source remote-sensing datasets in the GPM era. • The utility of integrated IMERG precipitation and GLEAM PET for drought monitoring was evaluated over mainland China. • SPEIs based on IMERG precipitation and GLEAM PET were validated at multiple spatial and temporal scales over mainland China. • IMERG precipitation and GLEAM PET show great potential for drought monitoring over eastern China and Southwest China. • SPEIs can well capture the temporal process and reasonably reflect the spatial characteristics for typical drought events. [ABSTRACT FROM AUTHOR]