Comparing methods to model the local gravity gradients from gravity anomalies

Abstract

The local modeling of gravity gradients is accomplished usually using digital elevation models through a forward computation based on straightforward Newtonian potential formulas and their derivatives. These models commonly neglect density variations within the topography as well as potentially significant density anomalies below the geoid. We consider the determination of gravity gradients from a dense grid of gravity anomalies, which by definition represent to total mass density variation, limited only in the resolution that is determined by the data grid spacing. Modeling the gradients from surface gravity anomalies, particularly at some altitude above ground, is based on numerical implementations of solutions to boundary-value problems in potential theory, such as Stokes’s integral, least-squares collocation, and some Fourier transform methods, or even with radial-basis splines. Modeling of this type would offer a complementary if not alternative type of support in the validation of airborne gradiometry systems. We compare these various modeling techniques using real and simulated data, thus demonstrating techniques and principles, as well as limitations and advantages in each.