Terrestrial water storage variation inferred from GRACE satellite and water balance

The GRACE satellite mission of gravity measurement launched in 2002 has been providing new information on terrestrial water storage (TWS) changes across the continents. Recent research has demonstrated that GRACE can be used to estimate TWS changes and other hydrologic quantities in large river basins. However, validation of GRACE water storage data remains difficult owing to the lack of data on TWS and its components, particularly over large areas. In this study, GRACE TWS will be compared with independent TWS estimates from other methods for selected regions and large river basins. Available in situ observations of soil moisture and groundwater depth are used to validate GRACE TWS data in Illinois. Seasonal and inter-annual TWS variations are explored by comparing GRACE TWS estimated from the combined (land-atmosphere) water balance (CWB) analysis for the selected large river basins. The primary goals of this study are to explore the potential for GRACE to observe TWS variations and to develop a framework for its validation.