Long-term and interannual variability of African terrestrial water storage revealed by GRACE/GRACE-FO and models

Climate change is intensifying the hydrologic cycle, and terrestrial water storage (TWS) provides an integrated indicator of these shifts. In this study, we analyzed long-term and interannual TWS variations across Africa over April 2002-December 2024 using GRACE/GRACE Follow-On (GRACE/-FO) satellite gravimetry, together with land surface models (LSMs) and satellite altimetry derived lake storage. GRACE/-FO revealed a continental TWS increase of 96.1 ± 13.4 Gt yr −1 (2σ), with an acceleration of 11.6 ± 3.83 Gt yr −2 . Basin-scale attribution exhibited that large lakes/reservoirs storage increases largely contributed to the observed TWS gains, whereas model predicted soil moisture showed a general declining trend, likely indicating the limitations of LSMs in this region. The long-term TWS increase was further quantitatively supported by a rising water balance. Interannual variability was structured by large-scale climate modes: El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) paced continental and tripole-like responses, respectively, as identified by empirical orthogonal function (EOF) analysis. Our results elucidated new observational constraints on the drivers of African TWS dynamics and their responses to a changing climate.