On the Contribution of Airborne Gravity Data to Gravimetric Quasigeoid Modeling: a Case Study in Mu Us Area, China

Airborne gravimetry has become increasingly important for geoid modeling since it is suitable for collecting large scale gravity data with uniform coverage and accuracy over inaccessible land areas and across costal zones. The question that how can the airborne gravity data contribute to the geoid determination arises. In order to quantitatively evaluate the contribution of airborne gravity to quasigeoid modeling, an intensive terrestrial survey encompassing airborne and terrestrial gravity, GPS and first order leveling was performed in Mu Us area, China. Based on the spectral combination approach, airborne gravity data were combined with satllite gravity models and terrestrial gravity data to compute sevaral gravimetric quasigeoid models. Validation results based on highly accurate GPS leveling derived height anomalies show that the accuracy of the quasigeoid models computed from the three data combination modes of GOCO05S & terrestrial gravity, GOCO05S & airborne gravity and GOCO05S & terrestrial & airborne gravity are 0.8 cm, 1.8 cm and 0.8 cm, respectively. Under the conditions of different spatial distribution and density of terrestrial gravity data, the quasigeoid solutions without and with airborne gravity data were compared and analyzed. The comparison results demostrate that in the cases of the average spacing of terrestrial gravity points exceeds 15 km, the additions of airborne gravity improve the accuracy of quasigeoid models by 11.1% - 48.3%.