[G03-4] Mass transport and redistrubution

[G03-4-03] Spatio-temporal downscaling of GRACE water storage changes data at catchment scale

^○Mohammad J. Tourian, Nico Sneeuw (Institute of Geodesy, University of Stuttgart)

The launch of the gravity mission GRACE satellites in 2002, caused a quantum leap both in hydrological understanding continental scale systems and their interactions as well as for applications. GRACE captures water storage change over landmasses, which is a useful indicator of climate variability and human impacts on the environment. The application of time variable gravity from GRACE for hydrological purposes has been growing. Recent achievements about the dynamic changes in groundwater highlight the importance of GRACE for hydrological applications. However, the spatio-temporal resolution remains the biggest bottleneck in applying GRACE-derived water storage changes to a wider hydrological use on regional catchments and shorter time scales as often needed for river basin management.
Although the spatio-temporal resolution of GRACE is limited by its orbit configuration, one can downscale water storage variation at catchment scale by assimilating the data of different storage compartments with a higher temporal and spatial resolution. This study attempts to develop a statistical based algorithm to achieve a realization of GRACE water storage with better temporal (less than a week) and spatial scales (~100 km), consistent with auxiliary observations. We use observations of hydrological and hydro-meteorological fluxes e.g. precipitation, runoff and moisture flux divergence. We also use surface water storage and soil moisture storage products. We estimate surface water storage by combining water level from satellite altimetry with the surface water extent from satellite imagery. We obtain spatio-temporal variable soil moisture storage from dedicated satellites e.g. SMOS ASCAT.