The collaborative research project RESEL-GRACE (Refined European sea level estimations by combining altimetry, tide gauges, hydrographic and other data sets with improved regional GIA modeling and tailored regional GRACE gravity field models) within the EUROCORES Programme
founded by the European Science Foundation (
) links the expertise in satellite geodesy, post-glacial rebound and sea level change research at TU Delft, GFZ and LEGOS Toulouse at national and European levels.
As one of the RESEL-GRACE project partner GFZ started its work in spring 2009 and is responsible for providing regional mean and time-variable gravity field models from GRACE instrument data for European regions of interest, in particular for the Mediterranean Sea and the North Sea/Fennoscandia region. These regional models will be computed for the full GRACE mission period with the same standards and conventions as currently planned for GFZ's next standard global monthly models (RL05, release in summer 2011). Further goals within the project RESEL-GRACE are the combination of multi-satellite altimetry data with GRACE measurements to explain water mass redistribution at the surface in the Mediterranean area as well as improving the knowledge of glacial isostatic adjustment with a coupled Earth-ice model constrained to satellite gravity data.
The prime GFZ RESEL-GRACE objective is the development of alternative representations of the gravity field besides the standard global GFZ GRACE processing procedure for a more suitable focusing on regional geophysical processes. One approach is the energy conservation law (the sum of kinetic and potential energies of the GRACE satellites must be constant at all times). With that, we directly transform in-situ GRACE K-Band range-rate observations as well as GPS-based orbit data (positions and velocities) into disturbing potentials. By using GRACE overflight data exclusively over an area of interest, e.g. the European Continent, the disturbing potential differences are further transformed into a multi-resolution representation (MRR). The MRR splits generally an input signal into a number of detail signals related to specific resolution levels, i.e., frequency bands.
© GFZ Potsdam
- Sample overflight track from GRACE (left) with corresponding in-situ observations in terms of geopotentials (top). Validation with reprocessed GPS data from dedicated European stations (right) is currently performed. Monthly mass distributions in terms of EWH for 2008 over Europe and with respect to EIGEN-5C (bottom)
Prof. Dr. Frank Flechtner