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A comparison of GPS, VLBI and model estimates of ocean tide loading displacements / I.D. Thomas in Journal of geodesy, vol 81 n° 5 (May 2007)
[article]
Titre : A comparison of GPS, VLBI and model estimates of ocean tide loading displacements Type de document : Article/Communication Auteurs : I.D. Thomas, Auteur ; Matt A. King, Auteur ; Peter J. Clarke, Auteur Année de publication : 2007 Article en page(s) : pp 359 - 368 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] analyse comparative
[Termes IGN] interférométrie à très grande base
[Termes IGN] positionnement par GPS
[Termes IGN] positionnement par ITGB
[Termes IGN] surcharge océaniqueRésumé : (Auteur) In recent years, ocean tide loading displacements (OTLD) have been measured using the Global Positioning System (GPS) and Very Long Baseline Interferometry (VLBI). This study assesses the accuracy of GPS measurements of OTLD by comparison with VLBI measurements and estimates derived from numerical ocean tide models. A daily precise point positioning (PPP) analysis was carried out on ?11 years of GPS data for each of 25 sites that have previous OTLD estimates based on data from co-located VLBI sites. Ambiguities were fixed to integer values where possible. The resulting daily estimates of OTLD, at eight principal diurnal and semi-diurnal tidal frequencies, were combined to give GPS measurements of OTLD at each site. The 3D GPS and VLBI measurements of OTLD were compared with estimates computed (by convolution with Green’s functions) from five modern ocean tide models (CSR4.0, FES2004, GOT00.2, NAO99b and TPXO6.2). The GPS/model agreement is shown to be similar to the VLBI/model agreement. In the important radial direction, the GPS/model misfit is shown to be smaller than the VLBI/model misfit for seven of the eight tidal constituents; the exception being the K2 constituent. Fixing of GPS carrier-phase ambiguities to integer values resulted in a marginal improvement to the GPS/model agreement. Statistically, it is shown there is no significance to the difference between the fit of the GPS and VLBI measurements of OTLD to modelled values. Equally, differences in fit of either the complete set of GPS or VLBI estimates to the five sets of model-derived values cannot be identified with statistical significance. It is thus concluded that, overall, we cannot distinguish between GPS and VLBI measurements of OTLD, and that at the global scale, present ocean tide models are accurate to within the current measurement noise of these techniques. Copyright Springer Numéro de notice : A2007-125 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0118-9 En ligne : https://doi.org/10.1007/s00190-006-0118-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28488
in Journal of geodesy > vol 81 n° 5 (May 2007) . - pp 359 - 368[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-07051 RAB Revue Centre de documentation En réserve L003 Disponible 266-07052 RAB Revue Centre de documentation En réserve L003 Disponible The topographic bias by analytical continuation in physical geodesy / Lard Erik Sjöberg in Journal of geodesy, vol 81 n° 5 (May 2007)
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Titre : The topographic bias by analytical continuation in physical geodesy Type de document : Article/Communication Auteurs : Lard Erik Sjöberg, Auteur Année de publication : 2007 Article en page(s) : pp 345 - 350 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] erreur systématique
[Termes IGN] formule de Stokes
[Termes IGN] géoïde terrestre
[Termes IGN] potentiel de pesanteur terrestreRésumé : (Auteur) This study emphasizes that the harmonic downward continuation of an external representation of the Earth’s gravity potential to sea level through the topographic masses implies a topographic bias. It is shown that the bias is only dependent on the topographic density along the geocentric radius at the computation point. The bias corresponds to the combined topographic geoid effect, i.e., the sum of the direct and indirect topographic effects. For a laterally variable topographic density function, the combined geoid effect is proportional to terms of powers two and three of the topographic height, while all higher order terms vanish. The result is useful in geoid determination by analytical continuation, e.g., from an Earth gravity model, Stokes’s formula or a combination thereof. Copyright Springer Numéro de notice : A2007-123 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0112-2 En ligne : https://doi.org/10.1007/s00190-006-0112-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28486
in Journal of geodesy > vol 81 n° 5 (May 2007) . - pp 345 - 350[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-07051 RAB Revue Centre de documentation En réserve L003 Disponible 266-07052 RAB Revue Centre de documentation En réserve L003 Disponible Practical geodesy : Part 2 The ellipsoid / Huibert-Jan Lekkerkerk in Geoinformatics, vol 10 n° 3 (01/04/2007)
[article]
Titre : Practical geodesy : Part 2 The ellipsoid Type de document : Article/Communication Auteurs : Huibert-Jan Lekkerkerk, Auteur Année de publication : 2007 Article en page(s) : pp 58 - 59 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie
[Termes IGN] ellipsoïde de référence
[Termes IGN] European Terrestrial Reference System 1989
[Termes IGN] North American Datum 1983
[Termes IGN] World Geodetic System 1984Résumé : (Auteur) In the previous article, it was stated that the earth could be approximated by a sphere or ellipsoid. The sphere is often used for simple navigation calculations, but for more accurate positioning the ellipsoidal shape of the earth has to be taken into account. Copyright GeoInformatics Numéro de notice : A2007-198 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28561
in Geoinformatics > vol 10 n° 3 (01/04/2007) . - pp 58 - 59[article]Determination of the free core nutation period from tidal gravity observations of the GGP superconducting gravimeter network / B. Ducarme in Journal of geodesy, vol 81 n° 3 (March 2007)
[article]
Titre : Determination of the free core nutation period from tidal gravity observations of the GGP superconducting gravimeter network Type de document : Article/Communication Auteurs : B. Ducarme, Auteur ; H.P. Sun, Auteur ; J.Q. Xu, Auteur Année de publication : 2007 Article en page(s) : pp 179 - 187 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] gravimètre supraconducteur
[Termes IGN] levé gravimétrique
[Termes IGN] marée océanique
[Termes IGN] pesanteur terrestre
[Termes IGN] réseau gravimétrique
[Termes IGN] surcharge océaniqueRésumé : (Auteur) This study is based on 25 long time-series of tidal gravity observations recorded with superconducting gravimeters at 20 stations belonging to the Global Geodynamic Project (GGP). We investigate the diurnal waves around the liquid core resonance, i.e., K 1, ?1 and ?1, to determine the free core nutation (FCN) period, and compare these experimental results with models of the Earth response to the tidal forces. For this purpose, it is necessary to compute corrected amplitude factors and phase differences by subtracting the ocean tide loading (OTL) effect. To determine this loading effect for each wave, it was thus necessary to interpolate the contribution of the smaller oceanic constituents from the four well determined diurnal waves, i.e., Q 1, O 1, P 1, K 1. It was done for 11 different ocean tide models: SCW80, CSR3.0, CSR4.0, FES95.2, FES99, FES02, TPXO2, ORI96, AG95, NAO99 and GOT00. The numerical results show that no model is decisively better than the others and that a mean tidal loading vector gives the most stable solution for a study of the liquid core resonance. We compared solutions based on the mean of the 11 ocean models to subsets of six models used in a previous study and five more recent ones. The calibration errors put a limit on the accuracy of our global results at the level of 1 0.1%, although the tidal factors of O 1 and K 1 are determined with an internal precision of close to 0.05%. The results for O 1 more closely fit the DDW99 non-hydrostatic anelastic model than the elastic one. However, the observed tidal factors of K 1 and ?1 correspond to a shift of the observed resonance with respect to this model. The MAT01 model better fits this resonance shape. From our tidal gravity data set, we computed the FCN eigenperiod. Our best estimation is 429.7 sidereal days (SD), with a 95% confidence interval of (427.3, 432.1). Copyright Springer Numéro de notice : A2007-182 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0098-9 En ligne : https://doi.org/10.1007/s00190-006-0098-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28545
in Journal of geodesy > vol 81 n° 3 (March 2007) . - pp 179 - 187[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-07031 RAB Revue Centre de documentation En réserve L003 Disponible 266-07032 RAB Revue Centre de documentation En réserve L003 Disponible Practical geodesy: Part 1 The basics / Huibert-Jan Lekkerkerk in Geoinformatics, vol 10 n° 2 (01/03/2007)
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Titre : Practical geodesy: Part 1 The basics Type de document : Article/Communication Auteurs : Huibert-Jan Lekkerkerk, Auteur Année de publication : 2007 Article en page(s) : pp 44 - 45 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie
[Termes IGN] coordonnées rectangulaires
[Termes IGN] ellipsoïde (géodésie)
[Termes IGN] projection Universal Transverse Mercator
[Termes IGN] système de coordonnéesRésumé : (Auteur) In our series on satellite navigation, the importance of the geodetic parameters was briefly discussed. They play a crucial role not only in positioning, but in cartography (and therefore GIS) as well. The geodetic knowledge within most organizations seems to be at two distinct levels. First there is a highly abstract level, with geodesy and geodetic calculations being practiced by the ‘true’ geodesist. On the other hand there is the GIS specialist or surveyor who is responsible for production and is led by the information given by the supplier. This article provides a general introduction to the subject for the surveyor. Copyright GEOinformatics Numéro de notice : A2007-191 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28554
in Geoinformatics > vol 10 n° 2 (01/03/2007) . - pp 44 - 45[article]Voir aussiRéservation
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Code-barres Cote Support Localisation Section Disponibilité 262-07021 SL Revue Centre de documentation Revues en salle Disponible Official geoid undulations model: substitute for nationwide orthometric control network / G. Steinberg in GIM international, vol 21 n° 2 (February 2007)PermalinkAufbau der neuen Landesvermessung der Schweiz 'LV95'. Teil 12 Landeshöhennetz 'LHN95' / A. Schlatter (2007)PermalinkPermalinkPermalinkA data set to test geoid computation methods / Henri Duquenne (01/01/2007)PermalinkPositionnement géodésique à haute fréquence de réseaux GNSS terrestres et marins / Stavros A. Melachroinos (2007)PermalinkQuelques définitions sur les systèmes de références et de coordonnées [diaporama] / Perrine Rouffiac (2007)PermalinkConversion altimétrique des hauteurs ellipsoïdales par GPS / A. Zeggai in XYZ, n° 109 (décembre 2006 - février 2007)PermalinkThe ellipsoidal correction to the Stokes kernel for precise geoid determination / M. Najafi-Alamdari in Journal of geodesy, vol 80 n° 12 (December 2006)PermalinkPermalink