Inversion of Moving-Base Gravity-Gradiometer Data for Geophysical Information

摘要

The increased speed and resolution possible with MBGG(Moving-Base Gravity Gradiometers) comes at a price, i.e. the need to cope wtih an enormous volume of data in the 5 independent gradient tensor components and the need for non-conventional methods for extracting geophysical information from the MBGG data. To address these needs, we conducted a survey of conventional and non-conventional data processing methods which might be applied to MBGG data processing. The conventional approach of simply integrating the gradient along the track of the moving platform to obtain a gravity profile ignores the information contained in the cross-track and vertical gradients. Furthermore, since the geophysicist is less interested in the gravity than in the underlying density distributions, conversion of MBGG data to gravity is a step in the wrong direction because of the inherent smoothing that integration entails. We show that the MBGG data contain much more information regarding the size, shape, and depth of buried structure than do conventional gravity data. This holds even when such structures are in isostatic equilibrium, such as a neutrally buoyant submarine, provided that the structures are not spherically symmetric. Among the non-conventional methods which showed promise derive and demonstrate an adaption of these methods for direct recovery of the topographic profile which gives rise to the measured gravity gradients. One interesting application arising from the use of this technique is the rapid profiling of bathymetry via aircraft survey.