Combining gravity and topographic data for local gradient modeling

Abstract

The local modeling of gravity gradients supports gradiometry systems by predicting observables whose residuals then yield new geophysical and geodetic information in the survey area. Gradients are usually modeled using local digital terrain elevation data (DTED). We supplement this with available (lower-resolution) gravity anomaly data for the longer-wavelength features and analyze the total model in terms of its spectral content over a local region such as the San Andreas Fault. New spherical models of transforming gravity anomalies to all components of the gradient tensor using Green's functions are developed and consistently combined with forward models of terrain elevation from very dense Shuttle Radar Topography Mission (SRTM) measurements. The modeling is applied to the case of airborne gradiometry at about 400 m over moderately rough terrain and yields an upper bound on the power spectral density to be expected in this case. Such gradient modeling should contribute to the design of appropriate filters in the processing of airborne gradiometric data. © Springer-Verlag Berlin Heidelberg 2007.