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Regional Models

Germany (GCG2011-NORTH)

  Authors: A. Rülke, et al.     Created: 2011    Resp: BKG  
      Status: PRIVATE    
The German Combined QuasiGeoid GCG2011 is a high-resolution hybrid model for Germany computed by the "Bundesamt für Kartographie und Geodäsie" (BKG) and the "Institut für Erdmessung" (IfE). The final solution was computed as the average of the two individual solutions from BKG and IfE. The GCG2011 model allows a direct transformation between ellipsoidal heights in the terrestrial reference system ETRS89 (SAPOS realization) and physical heights in the system DHHN92 (normal heights). The computation procedures at BKG and IfE are both based on the remove-restore technique. The input data are high-resolution gravity and terrain data, a global geopotential model, as well as GPS and levelling control points. The gravity stations (approx. 400,000) have a spacing of a few km, while the existing digital terrain model has a grid spacing of 1"x1" (corresponds to about 30 m block size). The BKG quasigeoid modelling is based on the adjustment of point masses that are located in grids at different depths. In a common adjustment of gravity and GPS/levelling data, the point masses are adjusted for given locations. The masses are then used for the derivation of quasigeoid undulations at any location. The quasigeoid modelling at IfE is based on integration and collocation techniques that are applied in a two-step procedure. In the first step, the gravity and terrain data are combined with the global geopotential model by spectral combination with integral formulas. This gravimetric solution is then combined in a second step with GPS and levelling data by collocation techniques. Contrary to the previous solution of IfE in 2003 (based on the EGG97 gravimetric geoid), this time a complete re-processing of all gravity and terrain data was done for the combination with GPS and levelling control points. The accuracy of the final GCG2011 was estimated as about 1-2 cm using partial solutions and independent GPS and levelling data. The model is available for users at the BKG geodata center.

G. Liebsch, U. Schirmer, J. Ihde, H. Denker, J. Müller (2006). Quasigeoidbestimmung für Deutschland. Deutscher Verein für Vermessungswesen - Schriftenreihe, 49, pp. 127-146.
A. Rülke, G. Liebsch, U. Schäfer, U. Schirmer, J. Ihde (2012). Geoid determination in Central Europe based on terrestrial data and GOCE observations. EGU General Assembly, 22-27 April 2012, Vienna, Austria.