ALBERT

Description: Airborne gravimetry is a crucial method to improve our knowledge about the Earth gravity field, especially in hard to access regions. Generally, the accuracy of airborne gravimetry is several mGal which is suitable for filling the so-called polar gaps in satellite-derived global gravity field models. Here, some investigations based on airborne gravity measurements from the GEOHALO mission over Italy are presented. To subtract the vertical accelerations from the values measured by the gravimeter, four different versions of kinematic accelerations were derived from Global Navigation Satellite Systems (GNSS) recordings. To remove the high-frequency noise, a low-pass filter with a cut-off wavelength of 200 s was applied to both, Chekan-AM measurements and kinematic accelerations from GNSS. To investigate how future airborne gravity campaigns could be designed, a dedicated flight track was repeated two times which showing that the equipment worked well also at higher altitude and speed. From the final best results follows an RMS of gravity differences at crossover points of 1.4 mGal which, according to the law of error propagation implies the accuracy of a single measurement to be  mGal. To demonstrate how a satellite-only gravity field model can be improved by airborne measurements, a gravity field model for the GEOHALO region has been computed. To compute also an improved regional geoid model, the point mass modeling (PMM) and the remove-compute-restore (RCR) technique, using a recent satellite-only model and residual terrain modeling (RTM), were applied. Finally, GNSS/Leveling points have been used to check the quality of the regional point mass model.