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IGS polar motion measurement accuracy / Jim Ray in Geodesy and Geodynamics, vol 8 n° 6 (November 2017)    

Public [article]  inGeodesy and Geodynamics > vol 8 n° 6 (November 2017) . - pp 413 - 420 Titre : IGS polar motion measurement accuracy Type de document : Article/Communication Auteurs : Jim Ray, Auteur ; Paul Rebischung , Auteur ; Jake Griffiths, Auteur Année de publication : 2017 Projets : 1-Pas de projet / Article en page(s) : pp 413 - 420 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] données GPS [Termes IGN] erreur systématique [Termes IGN] International GNSS Service [Termes IGN] mouvement du pôle [Termes IGN] orientation de la Terre [Termes IGN] paramètres d'orientation de la Terre [Termes IGN] précision du positionnement Résumé : (auteur) We elaborate an error budget for the long-term accuracy of IGS (International Global Navigation Satellite System Service) polar motion estimates, concluding that it is probably about 25–30 μas (1-sigma) overall, although it is not possible to quantify possible contributions (mainly annual) that might transfer directly from aliases of subdaily rotational tide errors. The leading sources are biases arising from the need to align daily, observed terrestrial frames, within which the pole coordinates are expressed and which are continuously deforming, to the secular, linear international reference frame. Such biases are largest over spans longer than about a year. Thanks to the very large number of IGS tracking stations, the formal covariance errors are much smaller, around 5 to 10 μas. Large networks also permit the systematic frame-related errors to be more effectively minimized but not eliminated. A number of periodic errors probably also influence polar motion results, mainly at annual, GPS (Global Positioning System) draconitic, and fortnightly periods, but their impact on the overall error budget is unlikely to be significant except possibly for annual tidal aliases. Nevertheless, caution should be exercised in interpreting geophysical excitations near any of the suspect periods. Numéro de notice : A2017-253 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : MATHEMATIQUE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.geog.2017.01.008 Date de publication en ligne : 02/03/2017 En ligne : https://doi.org/10.1016/j.geog.2017.01.008 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85261 [article]

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Basic Earth's Parameters as estimated from VLBI observations / Ping Zhu in Geodesy and Geodynamics, vol 8 n° 6 (November 2017)  

Public [article]  inGeodesy and Geodynamics > vol 8 n° 6 (November 2017) . - pp 427 - 432 Titre : Basic Earth's Parameters as estimated from VLBI observations Type de document : Article/Communication Auteurs : Ping Zhu, Auteur ; Attilio Rivoldini, Auteur ; Laurence Koot, Auteur ; Véronique Dehant, Auteur Année de publication : 2017 Article en page(s) : pp 427 - 432 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] analyse diachronique [Termes IGN] données ITGB [Termes IGN] interférométrie à très grande base [Termes IGN] nutation [Termes IGN] série temporelle Résumé : (auteur) The global Very Long Baseline Interferometry observation for measuring the Earth rotation's parameters was launched around 1970s. Since then the precision of the measurements is continuously improving by taking into account various instrumental and environmental effects. The MHB2000 nutation model was introduced in 2002, which is constructed based on a revised nutation series derived from 20 years VLBI observations (1980–1999). In this work, we firstly estimated the amplitudes of all nutation terms from the IERS-EOP-C04 VLBI global solutions w.r.t. IAU1980, then we further inferred the BEPs (Basic Earth's Parameters) by fitting the major nutation terms. Meanwhile, the BEPs were obtained from the same nutation time series using a BI (Bayesian Inversion). The corrections to the precession rate and the estimated BEPs are in an agreement, independent of which methods have been applied. Numéro de notice : A2017-790 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1016/j.geog.2017.04.007 En ligne : https://doi.org/10.1016/j.geog.2017.04.007 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89053 [article]