Results of creating an altitude-base using a local quasi-geoid model in the Republic of Lebanon

Abstract

The technology for determining the coordinates of points on the earth using the global navigation satellite system (GNSS) is becoming a standard along with ground-based methods. In this case, determining the plane coordinates of points does not cause any particular difficulties. However, to identify normal altitudes using this technique with a given accuracy, a special research is required. The fact is that according to satellite definitions, the geodetic height (H) is directly obtained, which differs from the normal one (HN) by an amount called height anomaly. This and the above mentioned value itself can be determined from the results of satellite leveling, taking into account the gravitational model of the Earth. But without clarification through ground measurements the result may not meet the required accuracy. In this work, geodetic and normal heights were determined for 5 control points in the Mount Lebanon region, where surveys were carried out using GNSS technology and geometric levelling. The obtained data were compared with satellite levelling one using the EGM2008 Earth model. In this case, geometric levelling was performed along different routes to ensure the information redundancy and determine average values. Thus, the normal heights obtained using the referred technology (quasi-geoid) served to correct those of the EGM2008 Earth model. The results of creating an altitudinal base in a local area corresponding to the foothill area are presented