Comparison of Astrogeodetic, Gravimetric, and Global Deflections of the Vertical: A Case Study in Colorado Test-Bed

Abstract

This paper assesses the accuracy and consistency of different methods for estimating the deflection of the vertical (DoV) and various geoid models in the Colorado test area. The DoVs derived from a gravimetric geoid model and several global geopotential models (GGMs) were inter-compared and validated by astrogeodetic DoVs. For the computation of global DoVs, two recent GGMs developed through data from the GOCE (The Gravity field and steady-state Ocean Circulation Explorer), GRACE (Gravity Recovery And Climate Experiment), and GOCE+GRACE satellite missions were utilized. Additionally, the astrogeodetic geoid heights were determined with the astronomical levelling method, while the gravimetric geoid heights were computed by the KTH (Swedish Royal Institute of Technology) method. The astrogeodetic, gravimetric, and GNSS-levelling geoid models were also cross-compared. The numerical results indicate that the DoVs obtained from the gravimetric geoid model are more accurate than those derived from global models. Moreover, in mountainous areas, the astrogeodetic geoid model provides a more precise solution than the other approaches.