REAL-GOCE

REAL-GOCE  (REal data AnaLysis GOCE) was a joint project of several German Research Institutes, namely the Rheinische Friedrich-Wilhelms-Universität Bonn, The Bundesamt für Kartographie und Geodäsie Frankfurt, Universität Hamburg, Deutsche Geodätisches Forschungsinstitut München, Technische Universität München, Universität Karlsruhe, Universität Stuttgart and Deutsches GeoForschungsZentrum Potsdam. The REAL-GOCE project was funded by the German Federal Ministry of Education and Research (BMBF) within its Geotechnologien Key Research Area "Observation of System Earth from Space III". The funding period for REAL-GOCE ended mid of 2012.

The scientific goal of REAL-GOCE consists of three thematic subtopics:  

1. GOCE gradient analysis and gravity field computation.
2. GOCE validation.
3. GOCE combination.

The main task of GFZ within the REAL-GOCE project belongs to subtopic 3 and comprises the computation of a high resolution Earth gravity field model including GOCE data. For this purpose GOCE satellite gradiometry data were combined for the first time with data from the satellite missions GRACE and LAGEOS and with surface gravity data. The resulting high-resolution model, EIGEN-6C reproduces mean seasonal variations and drifts to spherical harmonic degree and order (d/o) 50 whereas the mean spherical harmonic coefficients are estimated to d/o 1420. EIGEN-6C is based on satellite data up to d/o 240, which were combined with surface data only from degree 160 onwards The GOCE data allowed the combination with surface data at a much higher degree (160) than was formerly done (70 or less, for instance for EIGEN-5C), thereby avoiding the propagation of errors in the surface data over South America and the Himalayas in particular into the model. This can be seen in the figure below, where geoid height differences between EIGEN-6C and EGM 2008 up to d/o 1420 are shown in a global view and for Antarctica. In some regions of the globe, the difference patterns indicate impressively where the global gravity field modelling is enhanced by the novel GOCE data (e.g. in South America, the Himalayas, Central Africa or Antarctica). Furthermore, the GOCE polar gap can be clearly seen in Antarctica.