Development of the Geoid-Ellipsoid Separations Model

The state network of geodetic stations by means of the GPS measurements was created in Israel in 1990-2000. These geodetic stations were connected with the acting permanent network (APN) and high-grade GPS stations. Geographic coordinates of 7 APN stations in datum ITRF-2000 were used for the network adjustment. The ellipsoidal heights resulting from this adjustment are applied in the given model. Since the beginning of the project, the task of this network application was formulated so as to enable the network to determine the values of orthometric heights by means of the GPS measurements. Therefore the stations were created so that they would either coincide with the benchmarks or would be easily nivelled in the Datum of Israel orthometric heights. All such stations are expected to have both ellipsoidal and orthometric heights. Ellipsoid-geoid differences range from 16 to 24 meters on the territory of Israel. The model was developed on the basis of 684 points with the given ellipsoidal and orthometric heights. Geostatistical method of Kriging approximation was used for the construction of the undulation surface. The values of differences were calculated on the net 0.5 x 0.5 km. To define the accuracy of the undulation calculations the Kriging standar