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Fiducial reference systems for time and coordinates in satellite altimetry / Stelios Mertikas in Advances in space research, vol 68 n° 2 (15 July 2021)  

Public [article]  inAdvances in space research > vol 68 n° 2 (15 July 2021) . - pp 1140 - 1160 Titre : Fiducial reference systems for time and coordinates in satellite altimetry Type de document : Article/Communication Auteurs : Stelios Mertikas, Auteur ; Craig Donlon, Auteur ; Demetrios Matsakis, Auteur ; Constantin Mavrocordatos, Auteur ; Zuheir Altamimi , Auteur ; Costas Kokolakis, Auteur ; Achilles Tripolitsiotis, Auteur Année de publication : 2021 Projets : 3-projet - voir note / Article en page(s) : pp 1140 - 1160 Note générale : bibliographie Part of this work has been produced with the financial assistance of the European Union and the European Space Agency under the project FRM4S6 (Fiducial Reference Systems For Sentinel-6, No. 4000129892/20/NL/FF/ab) Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] altimétrie satellitaire par radar [Termes IGN] coordonnées cartésiennes géocentriques [Termes IGN] système de référence altimétrique Résumé : (auteur) Time is the fundamental measurement in satellite altimetry and the key parameter in building and keeping up a long-term, consistent, and reliable record for monitoring changes in sea level. Over the years, different time scales, although interconnected, have been used in altimetry and also in satellite positioning. This sometimes leads to inexplicit descriptions and ambiguous use of time and orbit coordinates as well as of their transformations between various reference and measuring systems. Altimetry satellites, like Sentinel-3, CryoSat-2, Jason-3, HY-2A/-2B, IceSat-2, etc., observe and practically realize ranges by measuring time differences between the transmission and reception of an electromagnetic wave (either radar or laser at present). Similar principles apply for global navigation satellite systems and for their terrestrial reference systems upon which altimetry is linked and tied together. Yet, the “meter” of any terrestrial reference systems is also defined by time. This work seeks to establish a standard reference system for “time” and “coordinates” in an effort to reach uniform and absolute standardization for satellite altimetry. It describes various errors generated from differences, discontinuities and interactions in time, frequency, range, time tagging, and reference coordinate frames. A new approach, called “fiducial reference measurements for altimetry”, is here given to examine ways to connect errors with metrology standards in order to improve the estimation of uncertainty budgets in ocean and water level observation by altimetry. Finally, the geocentric inertial reference system and the international atomic time are proposed in this paper for satellite altimetry observations and products. Numéro de notice : A2021-601 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2020.05.014 En ligne : https://doi.org/10.1016/j.asr.2020.05.014 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98240 [article]

Analytical and numerical methods of converting Cartesian to ellipsoidal coordinates / Georgios Panou in Journal of geodetic science, vol 11 n° 1 (January 2021)  

Public [article]  inJournal of geodetic science > vol 11 n° 1 (January 2021) . - pp 111 - 121 Titre : Analytical and numerical methods of converting Cartesian to ellipsoidal coordinates Type de document : Article/Communication Auteurs : Georgios Panou, Auteur ; Romylos Korakitis, Auteur Année de publication : 2021 Article en page(s) : pp 111 - 121 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] coordonnées cartésiennes géocentriques [Termes IGN] coordonnées ellipsoïdales [Termes IGN] transformation de coordonnées Résumé : (auteur) In this work, two analytical and two numerical methods of converting Cartesian to ellipsoidal coordinates of a point in space are presented. After slightly modifying a well-known exact analytical method, a new exact analytical method is developed. Also, two well-known numerical methods, which were developed for points exactly on the surface of a triaxial ellipsoid, are generalized for points in space. The four methods are validated with numerical experiments using an extensive set of points for the case of the Earth. Then, a theoretical and a numerical comparative assessment of the four methods is made. Furthermore, the new exact analytical method is applied for an almost oblate spheroid and for the case of the Moon and the results are compared. We conclude that, the generalized Panou and Korakitis’ numerical method, starting with approximate values from the new exact analytical method, is the best choice in terms of accuracy of the resulting ellipsoidal coordinates. Numéro de notice : A2021-983 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jogs-2020-0126 Date de publication en ligne : 04/12/2021 En ligne : https://doi.org/10.1515/jogs-2020-0126 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100982 [article]

Performance of a solution of the direct geodetic problem by Taylor series of Cartesian coordinates / Christian Marx in Journal of geodetic science, vol 11 n° 1 (January 2021)  

Public [article]  inJournal of geodetic science > vol 11 n° 1 (January 2021) . - pp 122 - 130 Titre : Performance of a solution of the direct geodetic problem by Taylor series of Cartesian coordinates Type de document : Article/Communication Auteurs : Christian Marx, Auteur Année de publication : 2021 Article en page(s) : pp 122 - 130 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] axe de rotation de la Terre [Termes IGN] coordonnées cartésiennes géocentriques [Termes IGN] ellipsoïde de révolution [Termes IGN] série de Taylor Résumé : (auteur) The direct geodetic problem is regarded on the biaxial and triaxial ellipsoid. A known solution method suitable for low eccentricities, which uses differential equations in Cartesian coordinates and Taylor series expansions of these coordinates, is advanced in view of its practical application. According to previous works, this approach has the advantages that no singularities occur in the determination of the coordinates, its mathematical formulation is simple and it is not computationally intensive. The formulas of the solution method are simplified in the present contribution. A test of this method using an extensive test data set on a biaxial Earth ellipsoid shows its accuracy and practicability for distances of any length. Based on the convergence behavior of the series of the test data set, a truncation criterion for the series expansions is compiled taking into account accuracy requirements of the coordinates. Furthermore, a procedure is shown which controls the truncation of the series expansions by accuracy requirements of the direction to be determined in the direct problem. The conducted tests demonstrate the correct functioning of the methods for the series truncation. However, the considered solution method turns out to be significantly slower than another current method for biaxial ellipsoids, which makes it more relevant for triaxial ellipsoids. Numéro de notice : A2021-984 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jogs-2020-0127 Date de publication en ligne : 13/12/2021 En ligne : https://doi.org/10.1515/jogs-2020-0127 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100983 [article]

A local projection for integrating geodetic and terrestrial coordinate systems / Mike Bremmer in Survey review, vol 52 n° 374 (August 2020)  

Public [article]  inSurvey review > vol 52 n° 374 (August 2020) . - pp 394 - 402 Titre : A local projection for integrating geodetic and terrestrial coordinate systems Type de document : Article/Communication Auteurs : Mike Bremmer, Auteur ; Marcelo Santos, Auteur Année de publication : 2020 Article en page(s) : pp 394 - 402 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Projections [Termes IGN] coordonnées cartésiennes géocentriques [Termes IGN] coordonnées géodésiques [Termes IGN] données GNSS [Termes IGN] géodésie terrestre [Termes IGN] méthode des moindres carrés [Termes IGN] projection [Termes IGN] projection stéréographique [Termes IGN] système de coordonnées Résumé : (auteur) This paper develops a system for projecting coordinates from a geocentric coordinate system to a topocentric coordinate system defined by terrestrial measurements. The proposed system uses an extension of the Stereographic Double Map Projection and a parametric least squares estimation to calculate the parameters for the map projection. The Extended Stereographic Double Projection and the projection parameter estimation are implemented and tested. Tests are performed to determine rate that discrepancies occur and the maximum extents of the Extended Stereographic Double Projection. This maximum area is determined to be ∼10 km2 with RMS values of residuals of 0.0029 m in northing and 0.0020 m in easting. Tests are also performed to determine the factor that limits the effective area of the Projection. Numéro de notice : A2020-516 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2019.1597490 Date de publication en ligne : 08/04/2019 En ligne : https://doi.org/10.1080/00396265.2019.1597490 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95676 [article]

A global vertical datum defined by the conventional geoid potential and the Earth ellipsoid parameters / Hadi Amin in Journal of geodesy, vol 93 n°10 (October 2019)  

Public [article]  inJournal of geodesy > vol 93 n°10 (October 2019) Titre : A global vertical datum defined by the conventional geoid potential and the Earth ellipsoid parameters Type de document : Article/Communication Auteurs : Hadi Amin, Auteur ; Lard Erik Sjöberg, Auteur ; Mohammad Bagherbandi, Auteur Année de publication : 2019 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] coordonnées cartésiennes géocentriques [Termes IGN] ellipsoïde de référence [Termes IGN] géoïde [Termes IGN] géoïde gravimétrique [Termes IGN] harmonique ellipsoïdale [Termes IGN] modèle de géopotentiel [Termes IGN] surface de la mer [Termes IGN] système de référence altimétrique [Termes IGN] système de référence géodésique Résumé : (auteur) 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 zero-degree 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 W0, 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 W0. 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 W0 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 W0. Our computations resulted in the geoid potential W0 = 62636848.102 ± 0.004 m2 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) × 106 m3 s−2. Numéro de notice : A2019-608 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-019-01293-3 Date de publication en ligne : 12/09/2019 En ligne : https://doi.org/10.1007/s00190-019-01293-3 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94791 [article]

Geodesic equations and their numerical solution in Cartesian coordinates on a triaxial ellipsoid / Georgios Panou in Journal of geodetic science, vol 9 n° 1 (January 2019)  

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Le CNIG et les références géodésiques / Françoise Duquenne in XYZ, n° 154 (mars - mai 2018)

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Les systèmes de référence terrestre et leurs réalisations : cas des territoires français / Françoise Duquenne in XYZ, n° 154 (mars - mai 2018)

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Amélioration des calculs GNSS à façon du SGN / Mathilde Kremp (2018) 

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TotalStation/GNSS/EGM integrated geocentric positioning method / Edward Osada in Survey review, vol 49 n° 354 (September 2017)  

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On the usefulness of relativistic space-times for the description of the Earth’s gravitational field / Michael Soffel in Journal of geodesy, vol 90 n° 12 (December 2016)  

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On the significance of periodic signals in noise analysis of GPS station coordinates time series / Janusz Bogusz in GPS solutions, vol 20 n° 4 (October 2016)  

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La mesure du niveau de la mer par bouées GPS : l'expérience multi-capteurs de l'île d'Aix / Gaël André in Navigation aérienne, maritime, spatiale, terrestre, vol 62 n° 246 (janvier 2015)

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Le positionnement par satellites et les coordonnées / Jonathan Chenal in Tangente, n° 157 (mars-avril 2014)

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Optimized formulas for the gravitational field of a tesseroid / Thomas Grombein in Journal of geodesy, vol 87 n° 7 (July 2013)  

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