Estimation of distant relief effect in gravimetry

Abstract

Abstract We analyze gravitational effects of distant topographic and bathymetric relief beyond the (earth-centered) angular distance of 1°29′58″ (i.e., beyond the outer limit of the Hayford-Bowie zone O, or approximately 167 km) using a spherical earth model. Our results support current procedures that neglect distant relief effects for most local gravity surveys but show their potential importance for continental- and global-scale surveys. The distant relief can produce horizontal gradients as large as 0.3 E (0.03mGal∕km). In mountainous areas, the gravitational effect of the distant relief is significant, even for local surveys, although the vertical gradient of the distant relief effect never exceeds ±30E(3mGal∕km) on the earth's surface.