Applications of Global Gravity Field Models in Geodesy and Oceanography

During the last decade, remarkable progress has been made in improving the gravitational models of the Earth and the terrestrial planets. The determination of these models has been accomplished using a wide variety of different measurement types and solution techniques. The measurement types for measuring the Earth’s potential field can be divided into satellite tracking measurements, surface gravity measurements, and satellite altimeter measurements; planetary gravity fields are determined exclusively from tracking data. Gravity field models accompanied by accurate error estimates are used to support a wide variety of applications including the orbit determination of spacecraft, a variety of geophysical investigations, oceanographic investigations using satellite altimetry, and for the definition of a unique vertical datum. The latter becomes increasingly important because of its implications in sea level studies and in the determination of orthometric heights and height differences from GPS positioning without the need for leveling. This paper will briefly review the progress made in recent gravity models, a spectrum of different applications of global gravity field models, and describe their ability to meet current requirements. In addition, the characteristics of the temporal variations of the gravity field will be reviewed with respect to obtaining a better understanding of important geophysical processes ongoing in the solid earth-ocean-atmosphere system. We will also review the current status of modeling planetary gravity fields, and discuss the applications of these models for geophysical studies and orbit determination. Finally, the prospects for improving current gravity models of the Earth and the planets will be discussed.