On Precision Kinematic Accelerations for Airborne Gravimetry

Advances in accelerometer technology promise many orders of magnitude improvement in sensitivity; which, consequently, also suggest progress in Earth Science applications, such as through new airborne gravimetric systems. However, a new capability for one sensor then usually demands commensurate requirements from auxiliary sensors in order to realize its full potential. Specifically, airborne gravimetry would benefit from improved inertial accelerometry only if the kinematic acceleration derived from vehicle tracking or positioning is equally precise. The latter is investigated in this study to determine the limits in precision due to errors in modeling the numerical derivative and due to errors in the positions, themselves. Simulations with actual aircraft trajectories show that the kinematic acceleration using current positioning capability (that is, GPS or similar satellite navigation systems) can be determined to an accuracy at the sub-milligal level only with sufficient smoothing over intervals of 60 s or longer. The effects of position error still dominate over the model error, and both are many orders of magnitude greater than the predicted precision of state-of-the-art accelerometry. This suggests that airborne gravity field determination likely will profit more if the advances in inertial sensor technology are directed toward gravity gradiometry.