Abstract:
The Gravity Recovery and Climate Experiment (GRACE) satellite mission provides unprecedented observations of variations in water stored at all levels above and below the land surface, but its low spatial and temporal resolutions, and inability to distinguish water storage components, make it challenging to apply for research and applications. We demonstrated that these issues can be effectively addressed by assimilating GRACE data into the Catchment land surface model (LSM). The experimental domain was the Mississippi River basin. Monthly GRACE estimates were derived for each of the four major sub-basins. Assimilation was performed using an ensemble smoother. In addition to simulating soil and snow water storages, the Catchment LSM accounts for variations in the elevation of the water table, making it appropriate for total terrestrial water storage applications. The assimilated results produced groundwater storage time series which more closely resembled piezometer based estimates, relative to the open loop simulations. Our results emphasize the potential for GRACE to improve the accuracy of hydrologic model output, which will benefit water cycle science and water resources applications.