The project “Tailored Regional Gravity Field Models for Mass Distribution and Mass Transport Phenomena in the Earth System” (TREGMAT) was part of the first funding period of the SPP1257. It is continued by the project REGHYDRO

Regional gravity field solutions from GRACE data

The global gravity field model ITG-GraceSpline03 was calculated from regional GRACE solutions as a refinement of the global model ITG-Grace03s ( www.geod.uni-bonn.de/itg-grace03.html ). Fig. 1 shows the impact of the regional focussing strategy by comparison with high resolution combination models and reveals a significant improvement of the RMS and the error stripe pattern. The improvements are particularly due to the use of specifically tailored space localizing basis functions and regional adaption of the downward continuation process. In this context, a regionally adapted regularization was introduced which takes into account the varying frequency behavior in different geographical areas, thus allowing to extract additional information out of a given data set. For more information see Eicker (2008) ( hss.ulb.uni-bonn.de/diss_online/landw_fak/2008/eicker_annette/eicker.htm )

Fig.1: Differences between Eigen-GL04c and ITG-Grace03s, (RMS 20.6 cm, left) and differences between Eigen-GL04c and ITG-GraceSpline03s, (RMS 17.9 cm, right)

Error distributions in regional inversion of potential fields from satellite data

The errors resulting from bounded data region have been intensively investigated

• The knowledge of these errors is important for the quality estimation of a regional potential field inversion

• Simulate inversions with synthetic data with a power spectrum following the Kaula rule; Monte-Carlo-Simulation in order to obtain expected mean errors

• Obtain estimations of the boundary region width required for a certain accuracy

Fig. 2 Errors for varying cap radii (left) and varying satellite altitudes (middle). Boundary width against desired accuracy (right)

Publications

Eicker, A., Mayer-Gürr, T. Ilk, K.H. (2008) Improved resolution of a GRACE gravity field model by regional refinements, Proceedings of the IUGG General Assembly, accepted for publication, Perugia, Italy

Eicker (2008) Gravity Field Refinement by Radial Basis Functions from In-situ Satellite Data, Dissertation at the University of Bonn, hss.ulb.uni-bonn.de/diss_online/landw_fak/2008/eicker_annette/eicker.htm

Mayer-Gürr, T. (2008) ITG-Grace03s, www.geod.uni-bonn.de/itg-grace03.html.