engleski

The contribution of the GRAV-D airborne gravity data in the regional geoid modelling: a case study in Colorado, USA

Already for few decades airborne gravity data has been used in the gravity and geoid modelling. Several countries have used such data for updating national gravity databases and gravimetric geoid development during height reference systems realization. Results related to the processing and usage of the GRAV-D airborne gravity data in the computation of the regional gravimetric geoid model in Colorado (USA) are presented in this study. The focus is to analyse spatial and spectral contributions of airborne gravity. The combination of airborne and terrestrial gravity data is not a straightforward process. Prior to the geoid computations, the data were processed in several procedures, including: filtering of the high-frequency observation noise, outliers removal, downward continuation, bias elimination, estimation of data stochastic properties and data gridding. After data preparation, different versions and solutions of the geoid models are computed by using Least Squares Modification of Stokes' formula with Additive corrections (LSMSA) regional geoid modelling approach. Three types of gravity anomaly grids are used as input data: airborne, terrestrial, and terrestrial-airborne. The accuracy of computed geoid models is estimated by their comparison with available GNSS/levelling points. The results show the geoid accuracy improves by more than 1 cm (20%) when airborne gravity is included in computations compared to the geoid models computed from the terrestrial gravity data only. Furthermore, the spectral analysis provided insights on specific wavelength bands in which airborne gravity data affects the geoid undulation power spectrum.

geoid ; airborne gravity ; downward continuation ; KTH ; spectrum

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