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The kinematics of Ny-Ålesund from space geodetic data / Halfdan Pascal Kierulf in Journal of geodynamics, vol 48 n° 1 (July 2009)  

Public [article]  inJournal of geodynamics > vol 48 n° 1 (July 2009) . - pp 37 - 46 Titre : The kinematics of Ny-Ålesund from space geodetic data Type de document : Article/Communication Auteurs : Halfdan Pascal Kierulf, Auteur ; Bjørn Ragnvald Pettersen, Auteur ; Daniel S. MacMillan, Auteur ; Pascal Willis , Auteur Année de publication : 2009 Article en page(s) : pp 37 - 46 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] marégraphe [Termes IGN] positionnement par DORIS [Termes IGN] positionnement par GPS [Termes IGN] positionnement par ITGB [Termes IGN] repère de référence [Termes IGN] Spitzberg [Termes IGN] station permanente Résumé : (auteur) We have compared coordinate time series from several space geodetic observing techniques to derive the kinematical motions of Ny-Ålesund, Svalbard. Velocity estimates from VLBI, GPS, and DORIS scatter more than the expected error estimates from each technique, and also between individual GPS solutions with different software and analysis strategies. A statistical combination yields average topocentric velocity components of mm/year (north), mm/year (east), and mm/year (vertical) for 1993–2007. The horizontal velocity is in agreement with a combined prediction of NUVEL-NNR-1A and the effects of post-glacial rebound and present day ice melt of nearby glaciers. The observed uplift is twice that predicted by the two latter processes. The non-linear time series of both VLBI and GPS data suggest that the uplift rate increases from 7.0 mm/year before 2003 to 10.8 mm/year after 2003. We conclude that this has a geophysical origin since no monument motions have been detected. A recent sea level decrease (1993–2007) of mm/year supports an absolute sea level increase of 3.2 mm/year as determined elsewhere by satellite altimetry. Numéro de notice : A2009-550 Affiliation des auteurs : IGN+Ext (1940-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.jog.2009.05.002 Date de publication en ligne : 14/05/2009 En ligne : https://doi.org/10.1016/j.jog.2009.05.002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89890 [article]

The gravitational effect of ocean tide loading at high latitude coastal stations in Norway / D.I. Lysaker in Journal of geodesy, vol 82 n° 9 (September 2008)  

Public [article]  inJournal of geodesy > vol 82 n° 9 (September 2008) . - pp 569 - 583 Titre : The gravitational effect of ocean tide loading at high latitude coastal stations in Norway Type de document : Article/Communication Auteurs : D.I. Lysaker, Auteur ; K. Breili, Auteur ; Bjørn Ragnvald Pettersen, Auteur Année de publication : 2008 Article en page(s) : pp 569 - 583 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] analyse comparative [Termes IGN] Arctique [Termes IGN] champ de pesanteur local [Termes IGN] champ de pesanteur terrestre [Termes IGN] correction du signal [Termes IGN] déformation de la croute terrestre [Termes IGN] levé gravimétrique [Termes IGN] littoral [Termes IGN] Norvège [Termes IGN] série temporelle [Termes IGN] surcharge océanique Résumé : (Auteur) Gravity measurements close to the ocean are strongly affected by ocean tide loading (OTL). The gravitational OTL effect consists of three parts, i.e. a change in gravity caused by direct attraction from the variable water-masses, by displacement of the observing point due to the load, and by redistribution of masses due to crustal deformation. We compare the OTL gravitational effect of several global models to observed time-series of gravity to identify the best model for four arctic observation sites. We also investigate if the global models are sufficient for correcting gravity observations. The NAO99b model fits the observations best at three stations. At two stations (Tromsø and Bodø) the global models explain the variability in the observations well. At the other two (Honningsvåg and Andøya), a significant periodic signal remains after the OTL correction has been applied. We separate two of the gravitational effects, the direct attraction and the change in gravity due to displacement, to study the local effects. Simple geometric models of the water load and independent measurements from local tide-gauges are used to calculate these effects. This leads to improved correspondence with the OTL signal, hence demonstrating the importance of careful modelling of local effects for correction of gravity observations in coastal stations. Copyright Springer Numéro de notice : A2008-351 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-007-0207-4 En ligne : https://doi.org/10.1007/s00190-007-0207-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29344 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-08081	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-08082	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Quasigeoid evaluation with improved levelled height data for Norway / D.I. Lysaker in Journal of geodesy, vol 81 n° 9 (September 2007)  

Public [article]  inJournal of geodesy > vol 81 n° 9 (September 2007) . - pp 617 - 627 Titre : Quasigeoid evaluation with improved levelled height data for Norway Type de document : Article/Communication Auteurs : D.I. Lysaker, Auteur ; O.C. Omang, Auteur ; Bjørn Ragnvald Pettersen, Auteur ; et al., Auteur Année de publication : 2007 Article en page(s) : pp 617 - 627 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] géoïde gravimétrique [Termes IGN] géoïde local [Termes IGN] nivellement par GPS [Termes IGN] Norvège [Termes IGN] rebond post-glaciaire Résumé : (Auteur) GPS-levelling points are widely used to control gravimetric geoid or quasigeoid models. Direct comparison is often interpreted to reveal the accuracy of the gravimetric model, using GPS-levelling as a reference. However, both GPS and levelled heights contain errors, and in order to achieve a centimeter-accuracy geoid, these should be investigated. The Norwegian Height System NN1954 is known to contain large systematic errors due to postglacial land uplift in the area. In this study, the current height system and two revised versions, corrected for uplift, are applied to compute three sets of control quasigeoid heights in the southern part of Norway. These heights are then compared to various Nordic gravimetric quasigeoid models generated during the last two decades. In contradiction to some earlier studies, the accuracy of gravimetric quasigeoid models for this area are found to improve near-linearly with time. This is in accordance with expectations, since both data coverage and computation methods have progressed during this time. However, this study shows the importance of establishing accurate and error-free control data for geoid comparisons. Copyright Springer Numéro de notice : A2007-391 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-006-0129-6 En ligne : https://doi.org/10.1007/s00190-006-0129-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28754 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-07071	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-07072	RAB	Revue	Centre de documentation	En réserve L003	Disponible