Use of GPCC and GPCP Precipitation Products and GRACE and GRACE-FO Terrestrial Water Storage Observations for the Assessment of Drought Recovery Times

Abstract. Meteorological and hydrological processes depend on accurate precipitation observations. Most precipitation products utilize station-based observations directly or to bias correct satellite retrievals. Thus, the validation of station-based precipitation products requires further independent data. This study aims to assess the accuracy of the Global Precipitation Climatology Center (GPCC) and Global Precipitation Climatology Project (GPCP) precipitation products by estimating hydrological drought recovery time (DRT) from terrestrial water storage anomaly (TWSA) acquired from satellite gravimetry and the required precipitation amount across the five main Köppen-Geiger climate zones. Station-based precipitation products, namely GPCC Full Data Monthly Product v2022 and GPCP v3.2 Monthly Analysis Product, were utilized to estimate DRT. Additionally, the JPL mascon and G3P Total Water Storage (TWS) monthly-solutions from the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) satellite missions were also employed for the DRT estimation. DRT was estimated through the following two methods: (1) storage deficit, determined as the negative residual of detrended TWSA from its climatology, and (2) required precipitation amount, derived from the linear relationship between cumulative detrended smoothed precipitation anomaly (cdPA) and detrended TWSA. The results show no significant differences in the mean DRT estimations using GPCC and GPCP. Conversely, DRT estimation using JPL mascon is 2.6 months longer on average than that using G3P. The equatorial zone showed the shortest DRT estimation, 10.3 months, while the polar zone had the longest, 16.2 months. Except for the polar zone, the arid zone shows the highest DRT estimations, 13.9 months. Consistency in DRT estimations between the two methods was high across the different climate zones, with the equatorial zone exhibiting the highest, 97.8 %, and the polar zone the lowest, 74.9 %. Similar to mean DRT estimation results, the differences in consistency were not significant for the estimations obtained from GPCC and GPCP. In contrast, the G3P showed approximately 5.0 % higher consistency than the JPL mascon. The findings based on DRT estimations indicate a close agreement between GPCC and GPCP. Moreover, G3P was more consistent in DRT estimation with precipitation products than JPL mascon. These results provide necessary information for precipitation and TWSA product accuracy by using the hydrological drought characteristics, which helps in understanding the meteorological and hydrological processes.