A Downscaled GRACE/GRACE-FO Terrestrial Water Storage Anomaly Product

The GRACE and GRACE-FO satellite missions provide mass variation data as a fundamentally new observation type for a wide range of novel applications in Earth science disciplines, including oceanography, geophysics, hydrology, and hydrometeorology. Despite significant findings in hydrology, the utility of GRACE-derived Terrestrial Water Storage Anomaly (TWSA) has been primarily limited to large catchments due to its coarse spatial resolution. Here, we present a downscaled TWSA product, along with its uncertainty, obtained through a Bayesian framework (presented in GRACE-Science Team meeting 2023) by incorporating fine-scale TWSA and soil moisture data from various sources. For the Bayesian framework, we rely on GRACE data to obtain the prior and use copula models to obtain nonparametric likelihood functions based on the statistical relationship between GRACE TWSA, fine-scale TWSF data, and soil moisture data. We present our new global data and discuss its strengths and limitations.