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The effect of using inconsistent ocean tidal loading models on GPS coordinate solutions / Y. Fu in Journal of geodesy, vol 86 n° 6 (June 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 6 (June 2012) . - pp 409 - 421 Titre : The effect of using inconsistent ocean tidal loading models on GPS coordinate solutions Type de document : Article/Communication Auteurs : Y. Fu, Auteur ; J. Freymueller, Auteur ; Tonie M. van Dam, Auteur Année de publication : 2012 Article en page(s) : pp 409 - 421 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] coordonnées GPS [Termes IGN] géocentre [Termes IGN] masse de la Terre [Termes IGN] surcharge océanique Résumé : (Auteur) We use up to a 6-year span of GPS data from 85 globally distributed stations to compare solutions using ocean tidal loading (OTL) corrections computed in different reference frames: center of mass of the solid Earth (CE), and center of mass of the Earth system (CM). We compare solution sets that differ only in the frame used for the OTL model computations, for three types of GPS solutions. In global solutions with all parameters including orbits estimated simultaneously, we find coordinate differences of ~0.3 mm between solutions using OTL computed in CM and OTL computed in CE. When orbits or orbits and clocks are fixed, larger biases appear if the user applies an OTL model inconsistent with that used to derive the orbit and clock products. Network solutions (orbits fixed, satellite clocks estimated) show differences smaller than 0.5 mm due to model inconsistency, but PPP solutions show distortions at the ~1.3 mm level. The much larger effect on PPP solutions indicates that satellite clock estimates are sensitive to the OTL model applied. The time series of coordinate differences shows a strong spectral peak at a period of ~14 days when inconsistent OTL models are applied and smaller peaks at ~annual and ~semi-annual periods, for both ambiguity-free and ambiguity-fixed solutions. These spurious coordinate variations disappear in solutions using consistent OTL models. Users of orbit and clock products must ensure that they use OTL coefficients computed in the same reference frame as the OTL coefficients used by the analysis centers that produced the products they use; otherwise, systematic errors will be introduced into position solutions. All modern products should use loading models computed in the CM frame, but legacy products may require loading models computed in the CE frame. Analysts and authors need to document the frame used for all loading computations in product descriptions and papers. Numéro de notice : A2012-243 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0528-1 Date de publication en ligne : 23/11/2011 En ligne : https://doi.org/10.1007/s00190-011-0528-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31689 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2012061	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Estimation of the zero-height geopotential level WoLVD in a local vertical datum from inversion of co-located GPS, leveling and geoid heights: a case study in the Hellenic islands / Christopher Kotsakis in Journal of geodesy, vol 86 n° 6 (June 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 6 (June 2012) . - pp 423 - 439 Titre : Estimation of the zero-height geopotential level WoLVD in a local vertical datum from inversion of co-located GPS, leveling and geoid heights: a case study in the Hellenic islands Type de document : Article/Communication Auteurs : Christopher Kotsakis, Auteur ; K. Katsambalos, Auteur ; Dimitrios Ampatzidis, Auteur Année de publication : 2012 Article en page(s) : pp 423 - 439 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] Egée, mer [Termes IGN] Grèce [Termes IGN] modèle de géopotentiel local [Termes IGN] niveau moyen des mers [Termes IGN] réseau altimétrique local [Termes IGN] zéro hydrographique Résumé : (Auteur) The estimation of the zero-height geopotential level of a local vertical datum (LVD) is a key task towards the connection of isolated physical height frames and their unification into a common vertical reference system. Such an estimate resolves, in principle, the ‘ambiguity’ of a traditional crust-fixed LVD by linking it with a particular equipotential surface of Earth’s gravity field under the presence of an external geopotential model. The aim of this paper is to study the estimation scheme that can be followed for solving the aforementioned problem based on the joint inversion of co-located GPS and leveling heights in conjunction with a fixed Earth gravity field model. Several case studies with real data are also presented that provide, for the first time, precise estimates of the LVD offsets for a number of Hellenic islands across the Aegean and Ionian Sea. Numéro de notice : A2012-244 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0530-7 Date de publication en ligne : 03/12/2011 En ligne : https://doi.org/10.1007/s00190-011-0530-7 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31690 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2012061	RAB	Revue	Centre de documentation	En réserve L003	Disponible