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Termes IGN > sciences naturelles > sciences de la Terre et de l'univers > géosciences > géophysique interne > géodésie > géodésie physique > figure de la Terre > surface de référence > géoïde
géoïde
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Terme(s) générique(s) :
géographie mathématique, géophysique, mesure. >> astronomie, gravité, arpentage. >>Terme(s) spécifique(s) : astronomie géodésique, aéronautique en géodésie, astronautique en géodésie, astronomie sphérique, azimut, isostasie, latitude, longitude, position géographique, satellite artificiel en géodésie, triangulation. Equiv. LCSH : Geodesy. Domaine(s) : 520; 550. Voir aussi |
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Titre : Géoïde : mythe ou réalité ? Type de document : Article/Communication Auteurs : Françoise Duquenne , Auteur ; François L'écu, Auteur ; Julien Gazeaux , Auteur Année de publication : 2017 Article en page(s) : pp 39 - 48 Note générale : Bibliographie Langues : Français (fre) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] altitude normale
[Termes IGN] altitude orthométrique
[Termes IGN] conversion altimétrique
[Termes IGN] géoïde
[Termes IGN] gravimétrie spatiale
[Termes IGN] mission spatiale
[Termes IGN] précision centimétrique
[Termes IGN] quasi-géoïde
[Termes IGN] récepteur GNSS
[Termes IGN] transformation de coordonnéesRésumé : (Auteur) Il devient dorénavant possible de déterminer la hauteur de n'importe quel sommet montagneux avec une précision centimétrique. Il suffit pour cela d'y monter avec un récepteur GNSS multifréquence, de respecter les temps d'observations et d'utiliser les méthodes de calculs précis. On peut alors atteindre ce centimètre tant désiré dans la détermination de la hauteur au-dessus d'un ellipsoïde et dans un référentiel géodésique bien précis. Pourtant dans les colonnes de la plupart des journaux (on remarquera ici que XYZ, ne fait pas partie du lot) on lit souvent que l'altitude a été mesurée au centimètre près. Le passage de la hauteur au-dessus de l'ellipsoïde à l'altitude n'a rien de trivial et le centimètre est difficile à obtenir dans cette transformation, même si comme on l'entend souvent il suffit d'utiliser un géoïde. Le but des lignes ci-dessous est, tout en reprenant les notions de base, de faire le point sur ce qu'on peut attendre en matière de géoïde et de conversion de hauteur en altitude. Numéro de notice : A2017-094 Affiliation des auteurs : IGN+Ext (2012-2019) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueNat DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84432
in XYZ > n° 150 (mars - mai 2017) . - pp 39 - 48[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 112-2017011 RAB Revue Centre de documentation En réserve L003 Disponible Documents numériques
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Géoïde : mythe ou réalité ? - pdf éditeurAdobe Acrobat PDF
Titre : Clock measurements to improve the geopotential determination Type de document : Article/Communication Auteurs : Guillaume Lion , Auteur ; Isabelle Panet , Auteur ; Pacôme Delva, Auteur ; David Coulot , Auteur ; Peter Wolf, Auteur ; Sébastien Bize, Auteur ; G. Christine, Auteur Editeur : Munich [Allemagne] : European Geosciences Union EGU Année de publication : 2017 Conférence : EGU 2017, General Assembly 23/04/2017 28/04/2017 Vienne Autriche https://www.egu2017.eu/ Note générale : LE POSTER N'EST PAS ENCORE ACCESSIBLE SUR HAL Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de gravitation
[Termes IGN] géoïde altimétrique
[Termes IGN] horloge optique
[Termes IGN] Massif central (France)
[Termes IGN] méthode des moindres carrés
[Termes IGN] précision centimétrique
[Termes IGN] qualité des donnéesRésumé : (Auteur) Comparisons between optical clocks with an accuracy and stability approaching the 10-18 in term of relative frequency shift are opening new perspectives for the direct determination of geopotential at a centimeter-level accuracy in geoid height. However, so far detailed quantitative estimates of the possible improvement in geoid determination when adding such clock measurements to existing data are lacking. In this context, the present work aims at evaluating the contribution of this new kind of direct measurements in determining the geopotential at high spatial resolution (10 km). We consider the Massif Central area, marked by smooth, moderate altitude mountains and volcanic plateaus leading to variations of the gravitational field over a range of spatial scales. In such type of region, the scarcity of gravity data is an important limitation in deriving accurate high resolution geopotential models. We summarize our methodology to assess the contribution of clock data in the geopotential recovery, in combination with ground gravity measurements. We sample synthetic gravity and disturbing potential data from a spherical harmonics geopotential model, and a topography model, up to 10 km resolution; we also build a potential control grid. From the synthetic data, we estimate the disturbing potential by least-squares collocation. Finally, we assess the quality of the reconstructed potential by comparing it to that of the control grid. We show that adding only a few clock data reduces the reconstruction bias significantly and improves the standard deviation by a factor 3. We discuss the role of different parameters, such as the effect of the data coverage and data quality on these results, the trade-off between the measurement noise level and the number of data, and the optimization of the clock data network. Numéro de notice : C2017-062 Affiliation des auteurs : LASTIG+Ext (2016-2019) Thématique : POSITIONNEMENT Nature : Poster nature-HAL : Poster-sans-CL DOI : sans Date de publication en ligne : 15/07/2022 En ligne : https://hal.science/hal-03724673v1 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101283 Documents numériques
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Clock measurements ... - posterAdobe Acrobat PDF On the spectral combination of satellite gravity model, terrestrial and airborne gravity data for local gravimetric geoid computation / Tao Jian in Journal of geodesy, vol 90 n° 12 (December 2016)
[article]
Titre : On the spectral combination of satellite gravity model, terrestrial and airborne gravity data for local gravimetric geoid computation Type de document : Article/Communication Auteurs : Tao Jian, Auteur ; Yan Ming Wang, Auteur Année de publication : 2016 Article en page(s) : pp 1405 - 1418 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] analyse harmonique
[Termes IGN] bruit blanc
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] erreur
[Termes IGN] géoïde gravimétrique
[Termes IGN] géoïde local
[Termes IGN] Texas (Etats-Unis)
[Termes IGN] varianceRésumé : (Auteur) One of the challenges for geoid determination is the combination of heterogeneous gravity data. Because of the distinctive spectral content of different data sets, spectral combination is a suitable candidate for its solution. The key to have a successful combination is to determine the proper spectral weights, or the error degree variances of each data set. In this paper, the error degree variances of terrestrial and airborne gravity data at low degrees are estimated by the aid of a satellite gravity model using harmonic analysis. For higher degrees, the error covariances are estimated from local gravity data first, and then used to compute the error degree variances. The white and colored noise models are also used to estimate the error degree variances of local gravity data for comparisons. Based on the error degree variances, the spectral weights of satellite gravity models, terrestrial and airborne gravity data are determined and applied for geoid computation in Texas area. The computed gravimetric geoid models are tested against an independent, highly accurate geoid profile of the Geoid Slope Validation Survey 2011 (GSVS11). The geoid computed by combining satellite gravity model GOCO03S and terrestrial (land and DTU13 altimetric) gravity data agrees with GSVS11 to ±1.1 cm in terms of standard deviation along a line of 325 km. After incorporating the airborne gravity data collected at 11 km altitude, the standard deviation is reduced to ±0.8 cm. Numerical tests demonstrate the feasibility of spectral combination in geoid computation and the contribution of airborne gravity in an area of high quality terrestrial gravity data. Using the GSVS11 data and the spectral combination, the degree of correctness of the error spectra and the quality of satellite gravity models can also be revealed. Numéro de notice : A2016-810 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0932-7 En ligne : http://dx.doi.org/10.1007/s00190-016-0932-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82602
in Journal of geodesy > vol 90 n° 12 (December 2016) . - pp 1405 - 1418[article]A conventional value for the geoid reference potential W0 / L. Sánchez in Journal of geodesy, vol 90 n° 9 (September 2016)
[article]
Titre : A conventional value for the geoid reference potential W0 Type de document : Article/Communication Auteurs : L. Sánchez, Auteur ; Robert Cunderlik, Auteur ; N. Dayoub, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 815 - 835 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] données GOCE
[Termes IGN] données GRACE
[Termes IGN] force de gravitation
[Termes IGN] géoïde terrestre
[Termes IGN] potentiel de pesanteur terrestre
[Termes IGN] surface de la mer
[Termes IGN] télémétrie laser sur satelliteRésumé : (auteur) W0 is defined as the potential value of a particular level surface of the Earth’s gravity field called the geoid. Since the most accepted definition of the geoid is understood to be the equipotential surface that coincides with the worldwide mean ocean surface, a usual approximation of W0 is the averaged potential value WS at the mean sea surface. In this way, the value of W0 depends not only on the Earth’s gravity field modelling, but also on the conventions defining the mean sea surface. W0 computations performed since 2005 demonstrate that current published estimations differ by up to −2.6 m2 s−2 (corresponding to a level difference of about 27 cm), which could be caused by the differences in the treatment of the input data. The main objective of this study is to perform a new W0 estimation relying on the newest gravity field and sea surface models and applying standardised data and procedures. This also includes a detailed description of the processing procedure to ensure the reproducibility of the results. The following aspects are analysed in this paper: (1) sensitivity of the W0 estimation to the Earth’s gravity field model (especially omission and commission errors and time-dependent Earth’s gravity field changes); (2) sensitivity of the W0 estimation to the mean sea surface model (e.g., geographical coverage, time-dependent sea surface variations, accuracy of the mean sea surface heights); (3) dependence of the W0 empirical estimation on the tide system; and (4) weighted computation of the W0 value based on the input data quality. Main conclusions indicate that the satellite-only component (n=200) of a static (quasi-stationary) global gravity model is sufficient for the computation of W0. This model should, however, be based on a combination of, at least, satellite laser ranging (SLR), GRACE and GOCE data. The mean sea surface modelling should be based on mean sea surface heights referring to a certain epoch and derived from a standardised multi-mission cross-calibration of several satellite altimeters. We suggest that the uncertainties caused by geographically correlated errors, including shallow waters in coastal areas and sea water ice content at polar regions should be considered in the computation of W0 by means of a weighed adjustment using the inverse of the input data variances as a weighting factor. This weighting factor should also include the improvement provided by SLR, GRACE and GOCE to the gravity field modelling. As a reference parameter, W0 should be time-independent (i.e., quasi-stationary) and it should remain fixed for a long-term period (e.g., 20 years). However, it should have a clear relationship with the mean sea surface level (as this is the convention for the realisation of the geoid). According to this, a suitable recommendation is to adopt a potential value obtained for a certain epoch as the reference value W0 and to monitor the changes of the mean potential value at the sea surface WS. When large differences appear between W0 and WS (e.g., >±2 m2 s−2), the adopted W0 may be replaced by an updated (best estimate) value. In this paper, the potential value obtained for the epoch 2010.0 (62,636,853.4 m2 s−2) is recommended as the present best estimate for the W0 value. It differs −2.6 m2 s−2 from the so-called IERS W0 value (62,636,856.0 m2 s−2), which corresponds to the best estimate available in 1998. Numéro de notice : A2016-655 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0913-x En ligne : http://dx.doi.org/10.1007/s00190-016-0913-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81857
in Journal of geodesy > vol 90 n° 9 (September 2016) . - pp 815 - 835[article]Use of the gyrotheodolite in underground networks of long high-speed railway tunnels / J. Velasco-Gómez, in Survey review, vol 48 n° 350 (September 2016)
[article]
Titre : Use of the gyrotheodolite in underground networks of long high-speed railway tunnels Type de document : Article/Communication Auteurs : J. Velasco-Gómez,, Auteur ; J. F. Prieto, Auteur ; I. Molina, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 329 - 337 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] déviation de la verticale
[Termes IGN] Espagne
[Termes IGN] géoïde
[Termes IGN] guidage de forage
[Termes IGN] guidage de véhicules
[Termes IGN] gyrothéodolite
[Termes IGN] lever souterrain
[Termes IGN] tunnel
[Termes IGN] voie ferréeRésumé : (auteur) The quality of geodetic networks for guiding Tunnel Boring Machines (TBMs) inside long tunnels depends largely on the correct use of a gyroscope. These networks are based on a series of control points at the tunnel entrance, and link each station by means of survey observations as they advance along the tunnel. Once, the networks are used to guide the TBM, they are no longer checked again. It is necessary to perform high accuracy astronomical observations to stars in order to determine the gyrotheodolite constant. Since astronomical observations cannot be made inside tunnels, geodetic azimuths have to be used for the computations. However, these azimuths cannot theoretically be compared with the astronomical azimuths obtained by the gyrotheodolite. An alternative is to compute the instrument constant using the values of the deviation of the vertical derived from a geoid model. That is the approach used in this work where a methodology for the design of underground networks in long tunnels is also presented. This procedure has been implemented during the construction of the Guadarrama and Pajares high-speed railway tunnels (Spain). Numéro de notice : A2016-640 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1179/1752270615Y.0000000043 En ligne : https://doi.org/10.1179/1752270615Y.0000000043 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81845
in Survey review > vol 48 n° 350 (September 2016) . - pp 329 - 337[article]A spatial analysis of GEOID03 and GEOID09 in Connecticut / Kazi Arifuzzaman in Journal of applied geodesy, vol 10 n° 2 (June 2016)PermalinkThe Canadian Geodetic Vertical Datum of 2013 (CGVD2013) / Marc Véronneau in Geomatica, vol 70 n° 1 (March 2016)PermalinkContribution of mass density heterogeneities to the quasigeoid-to-geoid separation / Robert Tenzer in Journal of geodesy, vol 90 n° 1 (January 2016)PermalinkPermalinkEléments de géodésie et de la théorie des moindres carrés / Abdelmajid Ben Hadj Salem (février 2016)PermalinkGravity field modelling and gravimetry / Jan Krynski in Geodesy and cartography, vol 64 n° 2 (December 2015)PermalinkThe status of measurement of the Mediterranean mean dynamic topography by geodetic techniques / Philip L. Woodworth in Journal of geodesy, vol 89 n° 8 (August 2015)PermalinkAccuracy of unmodified Stokes’ integration in the R-C-R procedure for geoid computation / Zahra Ismaïl in Journal of applied geodesy, vol 9 n° 2 (June 2015)PermalinkHow good is AUSGeoid09 in the Blue Mountains ? / Joseph Allerton in Position, n° 77 (June - July 2015)PermalinkGravité de la Terre : des mesures aux modèles, une image de la dynamique interne / Isabelle Panet (2015)Permalink