Satellite Gravity Field Missions: Status, Applications, and Future Prospects

Satellite gravity field missions are a unique measurement technique to image, probe and monitor mass transport processes in the Earth system. During the last decade, the three gravity missions CHAMP (Challenging Minisatellite Payload), GRACE (Gravity Recovery and Climate Experiment) and GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) have been monitoring the global gravity field and its tiny changes. Based on these data products, spectacular results could be achieved, enabling an improved understanding of Earth system processes such as the hydrological cycle, ice mass melting, ocean circulation, and earthquakes.

The derivation of gravity field maps from the original satellite data is a numerically expensive task and requires applying tailored algorithms and processing strategies, as well as high-performance computing. The GOCE mission alone gathered 800 million measurements, which have been crunched into a 75,000-parameter model describing the spatial variations of the Earth’s gravity field with a resolution down to 70 km. In order to increase further the spatial resolution, satellite data are combined consistently with terrestrial gravity field observations.

 An overview of the current missions’ status and achievements will be given, with attention to the impact that the resulting new-generation gravity field models are having on the main fields of application: i.e., global water cycle, ice melting in Greenland and Antarctica and their contribution to sea level rise, and global ocean circulation. Their potential to unify different height systems in use around the world will also be briefly discussed.

 The great success of these first-generation gravity field missions and their manifold applications in Earth sciences generated the need for a continuation of satellite gravimetry. Therefore, the talk will also review prospects for future missions to be realized in an international scope. Ideas on satellite constellations to increase spatial and temporal resolution will be discussed, as well as improved sensor technologies, which together should lead to an advanced monitoring system for mass transport processes in Earth’s system.