Newly Acquired Gravity Data in Support of the GeoNetGNSS CORS Network in Northern Greece

Abstract The main purpose of the GeoNetGNSS project, funded by the European Union and National Funds through the Region of Central Macedonia (RCM), is to establish a dense network of Continuously Operating Reference Stations (CORS) in northern Greece to support geodetic, surveying, engineering, and mapping applications. A regional, high-accuracy and high-resolution gravimetric geoid model is essential for the accurate determination of physical heights from CORS so as to transform the geometric heights into orthometric ones. In that frame and given the geological complexity and topographic peculiarities of the region, gravity campaigns have been designed and carried out around the newly established CORS stations to densify the already available land gravity database. The observations have been carried out employing the GravLab CG5 relative gravity meter and have been referred to GRS80/IGSN71, relative to the absolute gravity stations established by GravLab at the AUTH premises using the A10 (#027) absolute gravity meter. Moreover, dual-frequency GNSS receivers in network real time kinematic (NRTK) mode were used for orthometric height determination. Τhis work also leverages a database of previous gravity measurements to ensure the data coverage for the region. The XGM2019e Global Geopotential Model (GGM) has been used to model the low frequencies. Moreover, as the development of the geoid model is based on the Remove-Compute-Restore (RCR) technique and the Least Squares Collocation (LSC), the topographic corrections were calculated by the spectral Residual Terrain Model (RTM) method. In this work, the gravity anomalies derived from terrestrial gravity observations over the wider region of Central Macedonia are analyzed and compared with gravity anomalies derived from the XGM2016e GGM. The evaluation of the terrestrial gravity data was performed over six separate traverses, at various heights, in order to investigate the effect of height on the measurements. This technique allows for the comparison of the magnitude of gravity anomalies and the correlation with height, providing a more comprehensive understanding of the region’s gravitational field and possible improvement with the newly acquired data.