Test of Collocation Models for the Swiss Geoid Computation
Since Switzerland can be considered as a limited area with a limited amount of gravity field measurements, the new Swiss geoid computation is based on the multivariate collocation method. It has already been used successfully in the last national geoid computation (astro-geodetic geoid by Gurtner 1978) and in the geoid determination of Austria in 1983. This method is very suitable for combining different kinds of information about the gravity field such as deflections of the vertical, gravity measurements and ‘directly observed’ geoid undulations derived from levelling and GPS.
After the reduction of the observations we obtain a smoothed field of gravity field information which has now to be interpolated to the whole area. This step depends on the chosen variance-covariance functions of the collocation method. The influence of varying these functions in three different ways is presented in this paper.
In addition a short overview about a priori calculations of the errors of a predicted geoid is presented. There we can see that these errors depend more on the density of the used stations than on the chosen variance-eovariance model.
KeywordsGravity Field Gravity Measurement Geoid Undulation Orthometric Height Geoid Determination
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