The gravimetric geoid of Great Britain and Ireland

Abstract

The free-air co-geoid of Great Britain and Ireland was computed entirely by Stokes's integral, using mean free-air anomalies for 5" x 5", 1" x 1" and 10' x 20' compartments, with an estimated standard error of less than 1 m. Comparisons were made with astrogeodetic and Doppler-derived geoid heights, and values determined for the zero-order undulation and implied equatorial radius of the mean Earth ellipsoid. Geoid heights were also computed from GEM 10 potential coefficients.

Comparison of geosat and gravimetric geoid profiles in the North Sea

“…The region encompassing Great Britain and the western North Sea has excellent gravity coverage both on-and offshore (approximately one observation per square kilometer) and, as such, the area has been subject to a number of gravimetric geoid computations (e.g., Olliver, 1980;Stewart & Hipkin, 1990;Featherstone & Olliver, 1994;Hipkin, 1995). Since 1990, short-wavelength (<100-km) GPS/orthometric height geoid control has been available for the United Kingdom, with accuracy quoted by Hipkin (1995) of the order of 1-2 cm.…”

A Review of Geoid Models Over the British Isles: Progress and Proposals

“…Olliver [53,54] made the first gravimetric determination of the geoid of the British Isles. This model, herein termed OX79, used quadrature-based numerical integration for a direct application of the spherical Stokes formula including the then-available free-air gravity anomalies over the whole Earth, which was a challenge given the computational power available at that time.…”

A Review of Geoid Models Over the British Isles: Progress and Proposals

“…The same deflections of the vertical were used to produce an astrogeodetic geoid of the British mainland based on the European Datum 1950 and 1924 International Ellipsoid [53]. Olliver [56] transformed the OSGB70(SN) horizontal coordinates of these astrogeodetic stations to a geocentric datum to yield an astrogeodetically derived geoid with respect to the WGS84 ellipsoid.…”

“…The OX79 regional gravimetric co-geoid model refers to the GR67 ellipsoid and is given on a 10' by 20' (approximately 18km) grid bound by 50°N ≤ φ ≤ 60°N and 10°W ≤ λ ≤ 2°E. The standard error of OX79 was estimated internally to be approximately 1m [54]. Given the vintage of the gravity data, ellipsoid used, estimated precision and spatial resolution, OX79 is not suited to the best currently available transformation of GPSderived ellipsoidal heights.…”

“…Olliver [53,54] made the first gravimetric determination of the geoid of the British Isles. This model, herein termed OX79, used quadrature-based numerical integration for a direct application of the spherical Stokes formula including the then-available free-air gravity anomalies over the whole Earth, which was a challenge given the computational power available at that time.…”