A global vertical datum defined by the conventional geoid potential and the Earth ellipsoid parameters

Abstract

The geoid, according to the classical Gauss-Listing definition, is, among infinite equipotential surfaces of the Earth's gravity field, the equipotential surface that in a least squares sense best fits the undisturbed mean sea level. This equipotential surface, except for its zero-degree harmonic, can be characterized using the Earth's global gravity models (GGM). Although, nowadays, satellite altimetry technique provides the absolute geoid height over oceans that can be used to calibrate the unknown zerodegree harmonic of the gravimetric geoid models, this technique cannot be utilized to estimate the geometric parameters of the mean Earth ellipsoid (MEE). The main objective of this study is to perform a joint estimation of W 0 , which defines the zero datum of vertical coordinates, and the MEE parameters relying on a new approach and on the newest gravity field, mean sea surface and mean dynamic topography models. As our approach utilizes both satellite altimetry observations and a GGM model, we consider different aspects of the input data to evaluate the sensitivity of our estimations to the input data. Unlike previous studies, our results show that it is not sufficient to use only the satellite-component of a quasi-stationary GGM to estimate W 0 . In addition, our results confirm a high sensitivity of the applied approach to the altimetry-based geoid heights, i.e., mean sea surface and mean dynamic topography models. Moreover, as W 0 should be considered a quasi-stationary parameter, we quantify the effect of time-dependent Earth's gravity field changes as well as the time-dependent sea level changes on the estimation of W 0 . Our computations resulted in the geoid potential W 0 62636848.102 ± 0.004 m 2 s −2 and the semi-major and minor axes of the MEE, a 6378137.678 ± 0.0003 m and b 6356752.964 ± 0.0005 m, which are 0.678 and 0.650 m larger than those axes of GRS80 reference ellipsoid, respectively. Moreover, a new estimation for the geocentric gravitational constant was obtained as GM (398600460.55 ± 0.03) × 10 6 m 3 s −2 .

Determination of gravity anomalies in Java, Indonesia, from airborne gravity survey

“…The geoid represents the Earth's equipotential gravity surface which defines the definitive physical height reference in geodesy applications, i.e., orthometric height. This surface aligns with an ideal and undisturbed ocean surface, where tides, winds, and current influence were removed (Condi & Wunsch, 2004;Amin et al, 2019). In addition, the geoid extends through the continents, creating a seamless surface omnipresent.…”

Geomorphological modelling and mapping of the Peru-Chile Trench by GMT

“…A combination of several GMT modules is used for mapping geomorphological profiles based on the methodology of the GMT (P. Wessel et al 2019). As noted (H. Amin et al 2019), the Earth's gravity field is subject to temporal variations. Therefore, the geoid model is not a static surface.…”

Geodetic Altitude from Barometer and Weather Data for GNSS Integrity Monitoring in Aviation

“…In this work, we consider the WGS84 ellipsoid as the reference for the target geodetic altitude h, as it is currently the most widely used reference in navigation. A second possible reference surface is the Geoid, which is a model of the Earth's surface defined as the equipotential surface of the Earth's gravitational field, which best fits, in a least-squares sense, the global MSL (Amin et al, 2019). This is the level of the oceans averaged over the tide cycle.…”