Welcome to GravIS, the Gravity Information Service of the German Research Centre for Geosciences (GFZ), in collaboration with the Alfred-Wegener-Institut (AWI) and Technische Universität Dresden. Data products derived from the gravimetric Earth observation satellite missions GRACE and GRACE-FO are widely used by scientists and other interested users to study mass variations in the Earth system. However, processing of GRACE/GRACE-FO data into user-friendly products for dedicated geophysical applications is nontrivial, neither when starting from original satellite observations nor from the level of gravity field products. In order to enable the usage of satellite gravimetry data for a broader community, user-friendly ('Level-3') products are generated by various institutions.

GravIS visualizes and describes Level-3 products based on the most recent GRACE and GRACE-FO data release from GFZ. In addition, Level-3 products based on the most recent release of combined models for GRACE and GRACE-FO from COST-G are offered as well. The products presented at GravIS are available for download at GFZ's Information System and Data Center (ISDC) .

Further in-depth details on the GRACE and GRACE-FO missions and their applications is provided at GFZ's information portal globalwaterstorage.info . It offers up-to-date blog articles about recent research, background information about the missions and observables, and a collection of fact sheets, graphics and videos.

The Gravity Recovery and Climate Experiment (GRACE; 2002 - 2017) and its Follow-On mission (GRACE-FO; launched in May 2018) typically provide monthly independent estimates of the Earth's global gravity field. Differences between consecutive months are caused by mass redistribution and mass transport in the Earth system, particularly in the geophysical fluid layers of the atmosphere, oceans, and continental hydrosphere.

GRACE/GRACE-FO data processing is structured into sensor data analysis (Level-0 to Level-1), global gravity field estimation (Level-1 to Level-2), and geophysical mass anomaly inversion (Level-2 to Level-3). Level-3 products at GravIS comprise gridded mass anomalies as well as basin average time series and are available for terrestrial water storage over non-glaciated regions, bottom pressure variations in the oceans, and ice-mass changes in both Antarctica and Greenland. Additionally, GravIS also provides products of a prototype for monitoring groundwater storage anomalies which was developed within the EU Horizon 2020 project Global Gravity-based Groundwater Product (G3P) . In order to achieve the highest possible accuracy of the mass anomalies, several post-processing steps have been applied to the Level-2 spherical harmonic coefficients before inversion.