Airborne gravity gradiometry: Terrain corrections and elevation error

摘要

Terrain corrections for airborne gravity gradiometry dataare calculated from a digital elevation model (DEM) grid.The relative proximity of the terrain to the gravity gradiome-ter and the relative magnitude of the density contrast often re-sult in a terrain correction that is larger than the geologic sig-nal of interest in resource exploration. Residual errors in theterrain correction can lead to errors in data interpretation.Such errors may emerge from a DEM that is too coarselysampled, errors in the density assumed in the calculations, el-evation errors in the DEM, or navigation errors in the aircraftposition. Simple mathematical terrains lead to the heuristicproposition that terrain-correction errors from elevation er-rors in the DEM are linear in the elevation error but follow aninverse power law in the ground clearance of the aircraft.Simulations of the effect of elevation error on terrain-correc-tion error over four measured DEMs support this proposition.This power-law relation may be used in selecting an optimumsurvey flying height over a known terrain, given a desired ter-rain-correction error.