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Determination of the orthometric height difference based on optical fiber frequency transfer technique / Anh The Hoang in Geodesy and Geodynamics, vol 12 n° 6 (November 2021)
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Titre : Determination of the orthometric height difference based on optical fiber frequency transfer technique Type de document : Article/Communication Auteurs : Anh The Hoang, Auteur ; Ziyu Shen, Auteur ; Wenbin Shen, Auteur Année de publication : 2021 Article en page(s) : pp 405 - 412 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie
[Termes IGN] altimétrie
[Termes IGN] altitude orthométrique
[Termes IGN] coefficient de géopotentiel
[Termes IGN] fibre optique
[Termes IGN] fréquence
[Termes IGN] précision centimétriqueMots-clés libres : optical fiber frequency transfer Résumé : (auteur) The development of remote frequency transfer techniques, especially the appearance of optical clocks with unprecedented stability, has prompted geoscientists to study their applications in geodesy. Using remote frequency transfer technique, by frequency comparison of two optical clocks at two points P and Q connected by optical fibers, one can measure the signal's frequency shift between them, and the geopotential difference between them can be determined based on the gravity frequency shift equation. Given the orthometric height of P, the orthometric height of Q can be determined. Since the present stability of the optical clock has achieved 1 × 10−18 or better and comparing the frequency transfer via optical fiber provides stability at 10−19 level, the optical clock network enables determining the orthometric height at centimeter-level. This study provides a formulation to determine the height difference at one-centimeter level between two points on the ground based on the optical fiber frequency transfer technique. Numéro de notice : A2021-945 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1016/j.geog.2021.08.003 Date de publication en ligne : 22/09/2021 En ligne : https://doi.org/10.1016/j.geog.2021.08.003 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99757
in Geodesy and Geodynamics > vol 12 n° 6 (November 2021) . - pp 405 - 412[article]Optima multi-step collocation: application to the space-wise approach for GOCE data analysis / M. Reguzzoni in Journal of geodesy, vol 83 n° 1 (January 2009)
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Titre : Optima multi-step collocation: application to the space-wise approach for GOCE data analysis Type de document : Article/Communication Auteurs : M. Reguzzoni, Auteur ; N. Tselfes, Auteur Année de publication : 2009 Article en page(s) : pp 13 - 29 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] analyse harmonique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] coefficient de géopotentiel
[Termes IGN] collocation
[Termes IGN] GOCE
[Termes IGN] harmonique sphérique
[Termes IGN] levé gravimétriqueRésumé : (Auteur) Collocation is widely used in physical geodesy. Its application requires to solve systems with a dimension equal to the number of observations, causing numerical problems when many observations are available. To overcome this drawback, tailored step-wise techniques are usually applied. An example of these step-wise techniques is the space-wise approach to the GOCE mission data processing. The original idea of this approach was to implement a two-step procedure, which consists of first predicting gridded values at satellite altitude by collocation and then deriving the geo-potential spherical harmonic coefficients by numerical integration. The idea was generalized to a multi-step iterative procedure by introducing a time-wise Wiener filter to reduce the highly correlated observation noise. Recent studies have shown how to optimize the original two-step procedure, while the theoretical optimization of the full multi-step procedure is investigated in this work. An iterative operator is derived so that the final estimated spherical harmonic coefficients are optimal with respect to the Wiener–Kolmogorov principle, as if they were estimated by a direct collocation. The logical scheme used to derive this optimal operator can be applied not only in the case of the space-wise approach but, in general, for any case of step-wise collocation. Several numerical tests based on simulated realistic GOCE data are performed. The results show that adding a pre-processing time-wise filter to the two-step procedure of data gridding and spherical harmonic analysis is useful, in the sense that the accuracy of the estimated geo-potential coefficients is improved. This happens because, in its practical implementation, the gridding is made by collocation over local patches of data, while the observation noise has a time-correlation so long that it cannot be treated inside the patch size. Therefore, the multi-step operator, which is in theory equivalent to the two-step operator and to the direct collocation, is in practice superior thanks to the time-wise filter that reduces the noise correlation before the gridding. The criteria for the choice of this filter are investigated numerically. Copyright Springer Numéro de notice : A2009-179 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0225-x En ligne : https://doi.org/10.1007/s00190-008-0225-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29809
in Journal of geodesy > vol 83 n° 1 (January 2009) . - pp 13 - 29[article]Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 266-09011 RAB Revue Centre de documentation En réserve L003 Disponible 266-09012 RAB Revue Centre de documentation En réserve L003 Disponible Estimation of geopotential differences over intercontinental locations using satellite and terrestrial measurements / N.K. Pavlis (1991)
Titre : Estimation of geopotential differences over intercontinental locations using satellite and terrestrial measurements Type de document : Monographie Auteurs : N.K. Pavlis, Auteur Editeur : Colombus (Ohio) : Ohio State University Année de publication : 1991 Collection : Department of Geodetic Science and Surveying Reports num. 409 Importance : 155 p. Format : 21 x 27 cm Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] coefficient de géopotentiel
[Termes IGN] potentiel de pesanteur terrestreIndex. décimale : 30.40 Géodésie physique Numéro de notice : 12089 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54519 Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 12089-01 30.40 Livre Centre de documentation Géodésie Disponible
Titre : Determination of the geoid using heterogeneous data Type de document : Monographie Auteurs : Gérard Lachapelle, Auteur Editeur : Graz : Technische Universität Graz Année de publication : 1975 Collection : Mitteilungen der geodätischen Institute num. 19 Importance : 122 p. Format : 21 x 30 cm Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] anomalie de pesanteur
[Termes IGN] coefficient de géopotentiel
[Termes IGN] collocation par moindres carrés
[Termes IGN] covariance
[Termes IGN] déviation de la verticale
[Termes IGN] geoïde astro-géodésique
[Termes IGN] géoïde gravimétrique
[Termes IGN] harmonique sphériqueIndex. décimale : 30.41 Géoïde Résumé : (Auteur) The object of this work was to develop a method for determining the geoid over large territories using the following types of geodetic data: astrogeodetic deviations of the vertical, gravity anomalies, dynamic data in the form of geo-potential coefficients and topographic-isostatic deviations of the vertical.
In Part One, the application of least squares collocation to Molodenskii's, astrogravimetric levelling is considered. Instead of solving the fundamental equation of astrogravimetric levelling by classical methods, which involves much work for extensive applications, it was solved by least squares collocation. The least squares collocation solution offers important advantages in both practical and theoretical aspects. Practically, the solution presented here requires much less data preparation than previously because the observed deviations of the vertical and gravity anomalies can be used as such, regardless of their distribution; the interpolation is made automatically as it is contained implicitly in the fundamental equation of astrogravimetric levelling in least squares collocation. Theoretically, the contribution of the deviations of the vertical together with the gravity anomalies can be studied according to their distribution and accuracy; this is because least squares collocation can be directly applied to heterogeneous data. In this respect, important results are presented in Chapter IV. The use of geopotential coefficients is considered in Chapter III and the accuracy of the current geopotential coefficients solutions is studied. The improvement of accuracy attainable when removing low geopotential coefficients is also studied. The covariances, which play a basic role in the application of least squares collocation, are dealt with in Chapter II; several covariance functions for use in areas of flat and rugged topography are presented. Comparisons are made between the accuracy estimates obtained when using these covariance functions and those obtained when using Bomford's empirical formulae for astrogeodetic levelling; results are in good agreement; two Canadian astrogeodetic profiles were used for this purpose.
In Part Two, a method for estimating deviations of the vertical from a combination of topographic-isostatic deviations of the vertical with geopotential coefficients is presented. This method is especially well suited for large areas, either continental or oceanic, where no other geodetic measurements are available. It is ideally applicable in mountainous areas and along coastlines where the deviations depend much on the topography. Numerical results using topographic-isostatic deviations calculated in Canada, Switzerland and West-Germany are presented. The results of a geoid determination in Eastern Canada using these predicted deviations with the results obtained when using the corresponding observed deviations are also presented. Further possible improvements are proposed. A spherical harmonics expansion of the isostatic reduction potential, which is needed in connection with the method mentioned above, is presented; this method is rigorous within the usual spherical approximations made in physical geodesy.Numéro de notice : 44319 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Monographie Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=58196 Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 44319-01 30.41 Livre Centre de documentation Géodésie Disponible A study of the aliasing effect on gravitational potential coefficients as determined from gravity data / G.A. Desrochers (1971)
Titre : A study of the aliasing effect on gravitational potential coefficients as determined from gravity data Type de document : Rapport Auteurs : G.A. Desrochers, Auteur Editeur : Colombus (Ohio) : Ohio State University Année de publication : 1971 Collection : Reports of the Department of Geodetic Science Sous-collection : Scientific report num. 160 Importance : 70 p. Format : 21 x 27 cm Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] coefficient de géopotentiel
[Termes IGN] crénelage
[Termes IGN] levé gravimétriqueIndex. décimale : 30.40 Géodésie physique Numéro de notice : 45012 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Rapport de recherche Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=58273 Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 45012-01 30.40 Livre Centre de documentation Géodésie Disponible The direct combinaison of satellite and gravimetric data for mean anomaly determination / R.H. Rapp (1971)
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