Evaluation of EGM08 Using GPS and Leveling Heights in Greece

Abstract

AbstractThis paper presents an overview of the evaluation results for the new Earth Gravitational Model (EGM08) that was recently released by the US National Geospatial- Intelligence Agency, using GPS and leveled orthometric heights in the area of Greece. Various comparisons of geoid undulations obtained from the EGM08 model and other combined geopotential models, in conjunction with GPS/leveling data, have been performed in both absolute (at individual points) and relative (for baselines of varying length) sense. The test network covers the entire part of the Greek mainland and it consists of more than 1,500 ben- chmarks that belong to the Hellenic national triangulation network, with direct leveling ties to the Hellenic vertical reference frame. The spatial positions of these benchmarks have been recently determined at cm-level accuracy (with respect to ITRF2000) through an extensive national GPS campaign that was organized in the frame of the HEPOS project. Our results suggest that EGM08 offers a major improvement (more than 50%) in the agreement level among geoidal, ellipsoidal and orthometric heights over the mainland part of Greece, compared to the performance of previous global geopotential models for the same area.KeywordsEGM08GeoidEllipsoidal heightsOrthometric heightsGPS leveling