An improved GRACE-derived groundwater storage anomaly (igGWSA) dataset over global land with consideration of most non-groundwater components

Accurate monitoring of global groundwater storage anomaly (GWSA) is imperative for global water security and socio-economic sustainability. The Gravity Recovery and Climate Experiment (GRACE) satellite has emerged as a prevailing methodology for estimating GWSA by deducting non-groundwater components from terrestrial water storage anomaly (TWSA). However, in most previous studies, the accuracy of GWSA estimation suffers from inadequate consideration of non-groundwater components. Here we present an improved GRACE-derived GWSA dataset spanning 2000–2019 at the global scale, namely igGWSA, by taking into account most non-groundwater components including glaciers, permafrost, snow, lakes, reservoirs, profile soil moisture, and plant canopy water. igGWSA demonstrated strong agreement with well-observed groundwater level and model-simulated GWSA in five globally recognized hotspots of groundwater depletion, with the absolute value of correlation coefficient ranging from 0.94 to 0.99. Compared to igGWSA, inadequate consideration of non-groundwater components poses a significant potential impact on the accuracy of GWSA estimation in glacier-covered regions, permafrost zones, giant lakes, and deep-soil areas. For example, neglecting glaciers and permafrost would erroneously interpret glacier melting and permafrost degradation as part of changes in groundwater storage, respectively. The igGWSA is expected to serve global water security research, especially under a changing environment.