Global Earth Gravity Models

The Earth’s gravity field is the response to the internal mass density distribution of the Earth. A high-accuracy and high-resolution global gravity field information is a prerequisite for many branches of Earth Sciences. It is applied in geophysics to improve the modelling of the Earth’s interior, and geodynamic processes related to the lithosphere. In oceanography it will improve, in combination with satellite altimetry, the models of global ocean circulation, which is responsible for about 70-80 % of the global heat and energy transport, and the estimates for the mass balance of ice sheets, facilitating considerable progress in the climate change research. Also geodesy will highly benefit from it, because it will enable the unification of the vertical datum, and thus will allow levelling by the use of global positioning systems (GPS, Galileo). Therefore, in addition to a multitude of terrestrial campaigns to gather gravity data, recently the Earth’s gravity field is the focus of attention of the already launched or currently planned satellite missions CHAMP (CHAllanging Minisatellite Payload), GRACE (Gravity Recovery And Climate Experiment), and GOCE (Gravity Field and steady-state Ocean Circulation Explorer). The GOCE mission strives for a high-accuracy, high-resolution model of the Earth’s static gravity field, represented by spherical harmonic coefficients complete up to degree and order 250, which corresponds to a shortest half-wavelength of less than 100 km. In the framework of numerous national and international projects and initiatives, the Institute of Navigation and Satellite Geodesy has gained extensive experience in modelling of the Earth’s gravity field based on the satellite gravity missions CHAMP, GRACE, and GOCE, and related issues such as the solution of large systems of equations, and the statistical analysis of geodata. Research projects related to this field of research are: [EtomGal, EtomGal+, Level 1-2 Data Proc., DAPC, GFPF, HPF].