Regional gravity field models represent gravity field quantities at high spatial resolution. They are derived by combining satellite gravimetry with terrestrial, airborne, and marine gravity observations, thereby providing the highest possible spatial resolution of the Earth’s gravity field. Based on these models, point values or gridded representations of different gravity field functionals can be computed. While global gravity field quantities are derived from global gravity field models, providing coverage of the entire Earth, the regional gravity field quantities focus on specific regions or limited areas, allowing additional local observations to be incorporated, enabling a significantly higher spatial resolution than is achievable with global models alone.

To precisely determine the variations in the Earth’s gravity, geodesists use a mathematical model of the Earth as a reference body. This model is called the reference ellipsoid and is a mathematical apparatus of the planet. The reference ellipsoid has the same size and flattening as the Earth, contains the same mass as the Earth and rotates at the same rate as the Earth. These four properties make it possible to infer the ellipsoid’s gravity field, commonly known as the normal gravity field. Unlike the real Earth, the mass distribution inside the ellipsoid is assumed to be homogeneous. Geodesists therefore focus on identifying the differences in gravity between the real Earth and the ellipsoid.