Global Gravity Field Determination by Combining Goce and Complementary Data

GOCE gravity fields define a new standard concerning spectral resolution of satellite-only models, and provide a very high precision in the longand medium wavelength part of the gravity field up to a spherical harmonic degree of about 250. Combining GOCE with GRACE data, which gives in addition very accurate information for the long wavelength part, results in the current performance status of satellite-only models. By addition of terrestrial and altimetry data the spectral expansion can be enlarged even further, resulting in high-resolution gravity field models. High-resolution global gravity field determination based on heterogeneous input data puts high demands on computer resources, because full normal equations systems become very large, so that the assembling and solution processes are challenging with respect to memory and computing time. Therefore parallel methods have to be applied. At IAPG computations combining GOCE data with synthetic terrestrial data up to degree/order 600 have been performed. They have shown, that very large normal equation systems can be handled, concerning the processing steps assembling, solving, inversion as well as error propagation. In this study real terrestrial data shall be added consistently to the satelliteonly models. Here, further challenges like handling of inconsistent data sets and pre-processing of the terrestrial gravity data occur. This contribution shall present our first results of gravity field determination by using terrestrial, GOCE and GRACE data. The preparation and the relative weighting of the data sources shall be illustrated, analyzed and discussed. The contribution of GOCE to the combined model is explicitly visible.