Global gravity models and the Ghanaian Vertical Datum: challenges of a proper definition

This paper analyzes errors in satellite gravity and GPS/trigonometric benchmarks (BMs) in relation to defining the Ghanaian Vertical Datum (GhVD). Results indicate that synthesized gravity introduce approximately 5 mm of error to corrected heights. However, large errors in BMs render them unsuitable for applications, including properly defining the GhVD. Overall, normal-orthometric corrections were of the order of a few millimetres, with comparatively larger Helmert orthometric and normal corrections. Accordingly, the most suitable heights for the GhVD are the normal-orthometric heights, with the geopotential of the Helmert orthometric heights, 62636861.534±2.27 m2 s−2, suggested as the potential of the GhVD.