Assessment of recent global geopotential models based on the Auvergne test area data

Abstract

The gravitational field is important for many natural phenomena related to earth dynamics, especially mass transport. Its precise determination is essential for earth sciences such as geodesy, geophysics and oceanography. Determining the earth’s gravitational field is the same as determining the earth’s potential. Since this potential is a harmonic function outside the earth, spherical harmonic series are often used to represent the gravity field. Global Geopotential Models (GGMs) are sets of spherical harmonic coefficients representing the earth’s gravity field at different wavelengths. GGMs developed by scientists are published by the International Centre for Gravity Earth Models (ICGEM). When the structure of the GGMs is examined, it is seen that they consist of different degrees and various data groups. The accuracy and resolution provided by each GGM vary depending on the degree of the model and the data used for developing the GGM. Also, geodetic quantities such as potential, geoid undulation, deflection of the vertical components, gravity, and anomaly values can be derived from GGMs within the framework of mathematical principles. In this study, gravity, geoid heights, and free-air gravity anomaly values at test points using different GGMs produced in recent years have been investigated. The study area contains 98000 test points chosen from the Auvergne test area in France. Within the scope of the study, the geoid undulations, gravity values, and free-air gravity anomalies for all points derived from seven recent GGMs have been compared with ground-truth data and the statistical results have been obtained.