Comparison of Three Methods for the Downward Continuation of the Gravitational Gradients
Sprlak, Michal1; Novak, Pavel1; Valko, Milos2; Sebera, Josef3
1New Technologies for Information Society, Faculty of Applied Sciences, University of West Bohemia, CZECH REPUBLIC; 2Research Institute of Geodesy, Topography, and Cartography, CZECH REPUBLIC; 3Astronomical Institute, Academy of Sciences of the Czech Republic, CZECH REPUBLIC

The satellite gravitational gradiometry mission GOCE provides, among other products, gravitational gradients along the satellite's orbit. For geophysical applications, knowledge of the gravitational gradients at lower altitudes is required. In such a case, one has to deal with the downward continuation problem. Numerous methods have been proposed for downward continuation of potential field data. In this study, iterative, inverse, and direct evaluation methods are compared when gravitational gradients reduced to mean orbital radius are continued onto gravitational gradients at internal spherical surfaces. Several altitudes above the Earth surface and discretization sizes of input gradient grids are considered. Rigorous integration kernels are exploited in our numerical experiments.