Estimating the Gravity Disturbance Vector from Airborne Gravimetry

Abstract

In the past five years, considerable progress has been made in improving the accuracy of scalar gravimetry by integrated INS/DGPS sys- tems, both of the strapdown and the stable platform system type. Less attention has been given to vec- tor gravimetry and the results that have been pub- lished are much poorer in comparison. If the attitude components of the gravity disturbance vector could be determined with the same accuracy as its magni- tude, deflections of the vertical could be estimated with a standard deviation of about 0.3 arc seconds for a mimimum half-wavelength resolution of 1.5–2.0 km. This is not be possible at the moment. In this paper the reasons for the accuracy difference have been studied by analysing airborne gravity data taken over a well-determined reference field in the Canadian Rocky Mountains. Two different methods have been applied to determine the horizontal components of the gravity disturbance vector, i.e. the deflections of the vertical. In the first one, the standard method-direct deflection determination along individual profiles — has been used. In the second one, deflections have been estimated from gravity disturbances at flight level, using a modified Vening-Meinesz approach. The differences in results between the two methods clearly point to the large influence of gyro drifts in the direct deflection determination method.