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Regional Models

Auvergne - France (QGAuvergne)

  Author: H. Duquenne     Created: 2006    Resp: F. L'Ecu  
      Status: PUBLIC    
This is a gravimetric quasi-geoid model for Auvergne, that is considered as a testing area for different computation methods in the framework of the European Gravity and Geoid Project. The model is based on about 240000 gravity observations from the BGI database. A remove-restore procedure has been used for the quasi-geoid computation. The reference global gravity models has been obtained from a combination of GGM02S from degree 0 to 110 and EGM96 from degree 110 to 360. Two digital terrain models have been used, one of them providing normal heights referred to the NGF-IGN69 system, the other one providing heights above the GRS80 ellipsoid in the RGF93/ETRS89 system. Residual gravity anomalies have been converted into residual height anomalies by using the GRAVSOFT software package. Tests with fixed radius for Stokes’s integration (100 km, 150 km) gave less accurate results. The resulting quasi-geoid model extends for an area of 2°x3°, with a grid resolution of 1.5'x2' and it is referred to the GRS80 ellipsoid. A comparison of this gravimetric model with 75 GPS/levelling points yields an estimated accuracy of 3.8 cm, after applying a 3-parameter regression to the residuals.

H. Duquenne (2006). A data set to test geoid computation methods. Proceedings of the 1st International Symposium of the International Gravity Field Service, Istanbul, Turkey, Harita Dergisi, pp. 61-65.

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