Improving the Local Geoid with GPS

Abstract

We may get coordinates over WGS84, for a set of points in a geodetic net, by using GPS receivers. But these are geometric coordinates, so they do not have the physical meaning we usually need in the most of our geodetic and geodynamic works. From the global geoid we may get geodetic coordinates of those stations, by using interpolation. Then we can get the geoid undulation, and so the orthometric height. Now we have got a physical quantity to use in hydrographics, geographic information systems, airborne and ship borne navigators, geodynamics,... But the orthometric height accuracy will depend on the accuracy of the global Geoid Model. The aim of this work is to present a working method in order to get the local geoid undulation, using GPS, absolute and relative gravimetric measurements and high precision levelling in a small geographic area. Such method may be usefull in Hydrographics in order to get sounds in respect to the geoid.