Satellite gravimetry missions such as the on-going GRACE Follow-On (FO) mission, the planned GRACE-FO continuation mission as well as a Next Generation Gravity Mission (NGGM) that will form together with the GRACE-FO continuation mission the Mass-change and Geosciences International Constellation (MAGIC), are unique observing systems to measure the tiny variations of the Earth’s gravity field. Time-variable gravity derived by satellite gravimetry provides integrative measures of Terrestrial Water Storage (TWS) variations on a regional to global scale. Given the large interest of the scientific community to understand the processes of changes in TWS, comprising all the water storage on the Earth’s continental areas in frozen and liquid state, including ice caps, glaciers, snow cover, soil moisture, groundwater and the storage in surface water bodies and the interaction with ocean mass and sea level, TWS was adopted as a new Essential Climate Variable (ECV) in the implementation plan 2022 of the Global Climate Observing System (GCOS).
In this talk an overview of the underlying principles of the challenging satellite gravimetry data analysis is given and selected key scientific results and products are highlighted. A special focus is on European and international initiatives such as the Combination Service of Time-variable Gravity Fields (COST-G) of the International Association of Geodesy (IAG) and the H2020 project Global Gravity-based Groundwater Product (G3P) to exploit this unique observable in order to eventually derive the ECV Groundwater.
Groundwater is a most fundamental resource, but there is no service available yet to deliver data nor is there any other data source worldwide that operationally provides information on changing groundwater resources in a consistent, observation-based way with global coverage. By capitalizing from TWS derived from satellite gravimetry and from other satellite-based water storage compartments the H2020 project G3P established a prototype to provide groundwater storage change for large areas with global coverage that is planned to be included as a cross-cutting extension of the existing service portfolio of the European Union’s Earth Observation programme Copernicus.
Adrian Jäggi is the Director of the Astronomical Institute of the University of Bern (AIUB) in Switzerland. He is a Fellow of the International Association for Geodesy (IAG) and was president of IAG’s Commission 2 (Gravity Field) between 2019 and 2023. He initiated several international scientific projects in the field of space geodesy, among them projects funded by the Horizon 2020 Framework Program for Research and Innovation and the European Research Council, and is the founding Chair of IAG’s Combination Service of Time-variable Gravity fields (COST-G).
Webinar was recorded on September 28, 2023