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Regional Models

France (RAF98)

  Author: H. Duquenne     Created: 1998    Resp: F. L'Ecu  
      Status: PUBLIC    
RAF98 is a hybrid geoid model for France, covering the area 42° < lat < 51.5°, -5.5° < lon < 8.5° with a grid spacing of 1.5' in latitude and 2' in longitude. It is computed by fitting the QGF98 gravimetric quasi-geoid model to the nationwide RGF network of 987 GPS/levelling points by first removing a trend and then interpolating the residuals by kriging. Therefore the final model represents the height of the IGN69 reference surface above the GRS80 ellipsoid. Its validation based on an independent test dataset shows that a levelling by GPS relying on RAF98 is feasible with an overall precision of 2 to 3 cm, degrading to 4 cm in mountain areas.

H. Duquenne (1998). Grille de rorrection pour effectuer du nivellement par GPS. Revue Geometre, 6, juin 1998.
H. Duquenne (2002). Processus de conversions altimetriques applicables en France. In: Le GPS et les metiers du genie civil - Actes des journees scientifiques du LCPC, pp. 1-10.
IGN (2010). Descriptifs quasi-geoides et grilles de conversion altimetrique sur la France metropolitaine. Laboratoire de Recherche en Geodesie, Service de Geodesie et Nivellement.