International Service for the Geoid

Search in ISG Website



Services - Geoid Repository

Regional Models

Northwest Italy and
Switzerland (GISGEO2012)

  Authors: M. Gilardoni, M. Reguzzoni, D. Sampietro     Created: 2012    Resp: M. Reguzzoni  
      Status: PRIVATE    
GISGEO2012 is a gravimetric geoid for the Northwestern Italy and Switzerland, computed as a combination of the ITALGEO2005 and CHGEO2004 purely gravimetric solutions. In particular it covers the overlapping area from 45° to 47° in latitude and from 6.5° to 11° in longitude, with a grid resolution of 3'x3'. The choice of this area is related to the Helidem (HELvetia Italy Digital Elevation Model) project, requiring for the computation of a merged Italian-Swiss geoid. Basically the merging procedure consists of two steps. Firstly, a bias with respect to a satellite-only global gravity model was estimated for each of the two national geoids; in particular the 2nd release of the GOCE space-wise solution (GO_CONS_GCF_2_SPW_R2) was used as the reference global model. Secondly, the unbiased national geoids were combined by least-squares collocation, after removing and then restoring the global model contribution. Therefore the resulting GISGEO2012 model is referred to the WGS84 ellipsoid. Its assessment was performed by a comparison with GPS/levelling data in Switzerland, showing that the unbiased GISGEO2012 model slightly improves the accuracy of the original gravimetric geoid. It is classified as private in consistency with the distribution policy of the two original national models.

M. Gilardoni, M. Reguzzoni, D. Sampietro (2013). A least-squares collocation procedure to merge local geoids with the aid of satellite-only gravity models: the Italian/Swiss geoids case study. Bollettino di Geofisica Teorica ed Applicata, 54(4), pp. 303-319.