Reinterpreting Global GRACE Trends Based on Century‐Long GRACE‐REC Data

Abstract

AbstractAssessing changes in freshwater availability accurately is crucial for societal development. Previous studies have examined long‐term variations in basin‐scale terrestrial water storage (TWS) using Gravity Recovery and Climate Experiment (GRACE) mission data. However, different basins exhibit distinct spatial and temporal TWS variation patterns. To better interpret the TWS trends in each basin during the GRACE era (2003–2016), this study proposes a novel criterion based on a century‐long GRACE‐REC data set. This criterion assesses the trends in GRACE TWS (TrendG), precipitation‐induced trends (TrendPI), and non‐precipitation‐induced trends (TrendNPI) over the GRACE period. By calculating upper and lower bound values for long‐term climate‐driven TWS trends using GRACE‐REC data, an indicator is provided to evaluate the range of TWS trend variations in a basin under natural conditions. Results reveal that among the 266 global basins analyzed in this study, the trends (TrendG, TrendPI, or TrendNPI) in 115 basins exceed the maximum or minimum water storage trends associated with natural climate variability. This includes 20 large basins, 34 medium basins, and 61 small basins, indicating significant TWS changes during the GRACE period. Furthermore, we analyze the driving mechanisms of TWS trends in the 20 large basins using multi‐source data. The mechanisms identified through this method align well with both our analysis and previous studies, confirming the reliability of this approach for assessing TWS trends.