National Height Datum, the Gauss-Listing Geoid Level Value w 0 and Its Time Variation ẇ 0

Ardalan, Alireza A.; Grafarend, Erik W.; Kakkuri, Juhani

doi:10.1007/978-3-662-05296-9_3

Cited by 4 publications

(3 citation statements)

References 16 publications

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“…The methods proposed for datum unification exploit the availability of precise geoid models and GNSS observations at levelling benchmarks (see, e.g. Ardalan et al, 2002;Amos and Featherstone 2009) or are discussed in the theoretical frame of the Geodetic Boundary Value Problem (see, e.g. Xu 1992;Nahavandchi and Sjoberg 1998;Sansò and Venuti 2002;Sacerdote and Sansò 2004;Sjoberg 2011).…”

Section: Introductionmentioning

confidence: 99%

The worldwide physical height datum project

Barzaghi

Gaetani

Betti

2020

Rend. Fis. Acc. Lincei

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The definition of a common global vertical coordinate system is nowadays one of the key points in Geodesy. With the advent of GNSS, a coherent global height has been made available to users. The ellipsoidal height can be obtained with respect to a given geocentric ellipsoid in a fast and precise way using GNSS techniques. On the other hand, the traditional orthometric height is not coherent at global scale. Spirit levelling allows the estimation of height increments so that orthometric heights of surveyed points can be obtained starting from a benchmark of known orthometric heights. As it is well known, this vertical coordinate refers to the geoid, which is assumed to be coincident to the mean sea level. By means of a tide gauge, the mean sea level is estimated and thus a point of known orthometric height is defined. This assumption, which was acceptable in the past, became obsolete given the level of precision which is now required. Based on the altimetry observation, one can precisely quantify the existing discrepancy between geoid and mean sea level that can amount to 1 ÷ 2 m at global scale. Therefore, different tide gauges provide biased estimates of the geoid, given the discrepancy between this equipotential surface and the mean sea level. Also, in the last years, another vertical coordinate was used, the normal height that was introduced in the context of the Molodensky theory. In this paper, a review of the existing different height systems is given and the relationships among them are revised. Furthermore, an approach for unifying normal height referring to different tide gauges is presented and applied to the Italian test case. Finally, a method for defining a physical height system that is globally coherent is discussed in the context of the definition of the International Height Reference System/Frame, a project supported by the Global Geodetic Observing System of the International Association of Geodesy (IAG). This project was established in 2015 during the XXVI IAG General Assembly in Prague as described in IAG Resolution no. 1 that was presented and adopted there.

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Section: Introductionmentioning

confidence: 99%

The worldwide physical height datum project

Barzaghi

Gaetani

Betti

2020

Rend. Fis. Acc. Lincei

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“…As a different method from the global approach, Ardalan et al (2002) estimated W 0 to 62636855.75 ± 0.21 m 2 s −2 based on an ellipsoidal harmonic expansion of the external gravity field at the stationary GPS stations around the Baltic Sea. They also used regional tide gauge and GPS observations to study the secular variation in W 0 .…”

Section: Introductionmentioning

confidence: 99%

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

Amin

Sjöberg

Bagherbandi

2019

J Geod

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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 .

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“…Skaičiavimams naudota Lietuvos 1-osios klasės vertikaliojo tinklo matavimo ir išlyginimo duomenys (Adam et al 2000;Ardlan et al 2002;Moritz 1988;Skeivalas 2007Skeivalas , 2008. Tinklo mazginių taškų išlygintų altitudžių standartinių nuokrypių dėl parametrinių lygčių koeficientų klaidų įtakos įverčių vidutinė reikšmė gauta m m H a a  ( ) ( ) = ≈ τ 6 mm.…”

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Parametriniu lygčiu koeficientu klaidu itaka išlygintu parametru ir dydžiu tikslumui taikant mažiausiuju kvadratu metoda

Skeivalas

2008

Geodesy and Cartography

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National Height Datum, the Gauss-Listing Geoid Level Value w 0 and Its Time Variation ẇ 0

Cited by 4 publications

References 16 publications

The worldwide physical height datum project

The worldwide physical height datum project

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

Parametriniu lygčiu koeficientu klaidu itaka išlygintu parametru ir dydžiu tikslumui taikant mažiausiuju kvadratu metoda

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