Local gravity field modeling using surface gravity gradient measurements

Abstract

Almost 100,000 surface gravity gradient measurements exist in Hungary over an area of about 45 000 km2. These measurements are a very useful source to study the short wavelength features of the local gravity field, especially below 30 km wavelength. Our aim is to use these existing gravity gradient data in gravity field modeling together with gravity anomalies. Therefore we predicted gravity anomalies from horizontal gravity gradients using the method of least-squares collocation. The cross-covariance function of gravity gradients and gravity anomalies was estimated over the area and a suitable covariance model was estimated for the prediction. The full covariance matrix would require about 15 GB storage, however, the storage requirement can be reduced to about 300 MB by inspecting the structure of the cross-covariance function. Using sparse linear solvers the computation proved to be manageable, and the prediction of gravity anomalies for the whole area was performed. The results were evaluated at those sites where †g values were known from measurements in the computational area.