UNB application of Stokes–Helmert's approach to geoid computation

Abstract

Over the past two decades the so-called Stokes–Helmert method has been used for regional geoid determination at the University of New Brunswick (UNB). The present contribution summarizes the main principles of the UNB approach and successive theoretical developments. A two-space set-up is used for formulating the boundary value problem and defining gravity quantities, which would be appropriate for downward continuation from the Earth's surface to the geoid level. Focus of this paper is given on the topographical effects, which are formulated in their spherical form. UNB's solution of the Stokes boundary value problem employs a modified Stokes's formula in conjunction of the low-degree contribution of a global geopotential model (GGM). Various aspects at the regional geoid computations in the context of UNB's principles are illustrated by employing a new GRACE satellite mission based geopotential model for the numerical study. The new gravimetric geoid model is compared with local GPS-levelling data. Possible reasons of the detected discrepancies between the gravimetric geoid model and the control points are discussed.