Practical aspects of terrain correction in airborne gravity gradiometry surveys^*

Abstract

Proper terrain correction in onshore airborne gravity gradiometry surveys requires detailed digital elevation models (DEMs). However, the horizontal resolution requirement of DEMs is not well explored in literature. As a result, there is no standardized horizontal resolution used in commercial surveys. Also, the effect of requisite low-pass filtering applied during and subsequent to acquisition has not been discussed within this context. We address these issues by quantifying the optimal horizontal resolution using an example dataset and a practical method for performing terrain corrections in barometric surveys, based on Parker’s 1972 Fourier-domain calculation. We also quantify the required spatial extents of DEMs (including grid padding) by deriving empirical rules based on numerical simulations. With these parameters quantified, we provide the basis for optimising the terrain correction to improve efficiency in not only gravity gradiometry terrain corrections and forward modelling, but also in DEM acquisition survey design.