ITSG-Grace2016 - Daily Gravity Field Solutions from GRACE

The Gravity Field And Climate Experiment (GRACE) has granted invaluable insight into the redistribution of surface mass, by providing monthly snapshots of the Earth’s gravity field. Highly dynamic events like floods, which can build up and drain on time scales from hours to weeks, are however difficult to resolve with this comparatively coarse sampling rate of one month. To capture such short-lived processes, an increased temporal resolution of the GRACE solutions is necessary. Yet, such an increase in temporal resolution comes at the cost of reduced spatial sampling. To still be able to derive global gravity fields from only one day of GRACE data and the subsequent limited data coverage, additional information is required. We use stochastic information from geophysical models to effectively constrain the limited GRACE data in space and time. ITSG-Grace2016 is the latest time series of GRACE solutions based on this approach, providing daily, global, Kalman smoothed gravity field snapshots. The release covers the complete GRACE observation time span starting from April 2002 and is continuously updated. We show the added value of the daily solutions by comparison with in-situ data and output from different global hydrological models. High frequent variations in river discharge are well reflected in the GRACE derived total water storage anomalies for mid- to large scale flood events. These comparisons suggest that daily GRACE products contain high-frequency gravity field information and represent are a suitable data source for the monitoring of hydrological extreme events.