International Service for the Geoid


Search in ISG Website




Services - Geoid Repository

Regional Models

Switzerland and Liechtenstein (CHGeo98)

  Author: U. Marti     Created: 1998    Resp: U. Marti  
      Status: PUBLIC    
The CHGeo98 geoid and quasi-geoid model of Switzerland was computed by Federal Office of Topography (Swisstopo) and it was the official geoid model in Switzerland and Liechtenstein from 1998 to 2004. It covers the area from 45° 45' N to 47° 51' N in latitude and from 5° 51' E to 10° 30' E in longitude with a grid resolution of 30". It is referred to the GRS80 normal ellipsoid in the ETRS89/CHTRF95 frame. It is a hybrid model because it was computed by combining astrogeodetic data (about 600 deflections of the vertical), gravimetric data (more than 3500 gravity measurements) and GPS/levelling data (about 70 stations). The raw observations were 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. The CHGeo98 geoid model is compatible with the Swiss orthometric heights in LHN95, whereas the CHQua98_EF quasi-geoid model is compatible with the EVRF2000 height datum, which is shifted by 10.31 cm from the Swiss normal heights in LHN95.

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.

Web of Science ID:

   Retrieve file