Higher Temporal Resolution Global GRACE/GRACE-FO Total Water Storage Products for Assimilation in Hydrology Models

The Gravity Recovery and Climate Experiment (GRACE) and its Follow-On (GRACE-FO) missions have provided near continuous and unique measurement of total water storage  (TWS) since 2002. These international partnership missions have provided valuable insights in the fields of Hydrology, Oceanography, Ocean dynamics, Cryosphere Sciences, Solid Earth etc. These data from GRACE/GRACE-FO have improved our understanding of the Earth’s water cycle since launch and have become indispensable for climate related studies.

The spatial resolution of the data products from GRACE/GRACE-FO are roughly 300km and they typically have a temporal resolution of a month. These products provide the unique measurement of the total water storage of the entire water column and can provide a constraint for hydrological and ocean models. Several studies have used GRACE products for assimilation into the hydrological models for improved assessment of the reality on the ground and for downscaling the information to a higher spatial resolution using data assimilation. This paper will introduce the techniques that improve of temporal resolution of GRACE/GRACE-FO products from month to shorter than 5 days. That includes production of global 5-day TWS solution and the daily TWS product from GRACE that is estimated as a “swath” over the daily satellite ground-track.  The paper will discuss the analysis results over hydrological and ocean basins and validate the higher frequency signals captured by this product.  The goal for the production of this higher temporal resolution GRACE/GRACE-FO product is to be able to use these signals with a latency of a few days for ingestion into machine learning algorithms for early flood detection applications and for daily assimilation into hydrological models at short latency.