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Regional Models

Switzerland (CHGEO98)

  Author: U. Marti     Created: 1998    Resp: U. Marti  
      Status: PRIVATE    
The CHGEO98 geoid and quasigeoid model of Switzerland was computed by Federal Office of Topography (Swisstopo). It is referred to the GRS80 normal ellipsoid in the ETRS89/CHTRF95 frame and the height datum is LHN95. It was determined by combining astrogeodetic data (about 600 deflections of the vertical), gravimetric data (about 3500 gravity measurements) and GPS/levelling data (about 70 stations). The raw observations have been reduced by the influence of mass models, including topography (based on a digital terrain model with a resolution of 25 m), Moho and several local density anomalies such as the Ivrea body, sediments of large rivers, water of lakes, ice of glaciers, etc. No global geopotential model was introduced in the data reduction. From the residual gravity field, the geoid as well as the quasi-geoid were obtained by least squares collocation in the framework of a remove-compute-restore procedure. Both solutions are supposed to have an accuracy of about 3 cm in the flatter areas and about 5 cm in mountainous regions, as it was verified by comparison with the independent European Gravimetric Geoid EGG97. The GPS/levelling residuals are in the order of ±8 cm with a rather smooth behaviour.

U. Marti (2002). Das Geoid der Schweiz 1998 "CHGEO98". Swisstopo Doku, Bericht 16, Teil 10.
U. Marti (2004). High Precision combined geoid determination in Switzerland. Proc. of the IAG GGSM2004 Symposium, Porto, Portugal.

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