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The impact of errors in polar motion and nutation on UT1 determinations from VLBI Intensive observations / Axel Nothnagel in Journal of geodesy, vol 82 n° 12 (December 2008)
[article]
Titre : The impact of errors in polar motion and nutation on UT1 determinations from VLBI Intensive observations Type de document : Article/Communication Auteurs : Axel Nothnagel, Auteur ; D. Schnell, Auteur Année de publication : 2008 Article en page(s) : pp 863 - 869 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] compensation
[Termes IGN] données ITGB
[Termes IGN] écart type
[Termes IGN] erreur systématique
[Termes IGN] mouvement du pôle
[Termes IGN] nutation
[Termes IGN] temps universelRésumé : (Auteur) The earth’s phase of rotation, expressed as Universal Time UT1, is the most variable component of the earth’s rotation. Continuous monitoring of this quantity is realised through daily single-baseline VLBI observations which are interleaved with VLBI network observations. The accuracy of these single-baseline observations is established mainly through statistically determined standard deviations of the adjustment process although the results of these measurements are prone to systematic errors. The two major effects are caused by inaccuracies in the polar motion and nutation angles introduced as a priori values which propagate into the UT1 results. In this paper, we analyse the transfer of these components into UT1 depending on the two VLBI baselines being used for short duration UT1 monitoring. We develop transfer functions of the errors in polar motion and nutation into the UT1 estimates. Maximum values reach 30 [?s per milliarcsecond] which is quite large considering that observations of nutation offsets w.r.t. the state-of-the-art nutation model show deviations of as much as one milliarcsecond. Copyright Springer Numéro de notice : A2008-470 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0212-2 En ligne : https://doi.org/10.1007/s00190-008-0212-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29539
in Journal of geodesy > vol 82 n° 12 (December 2008) . - pp 863 - 869[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-08111 RAB Revue Centre de documentation En réserve L003 Disponible 266-08112 RAB Revue Centre de documentation En réserve L003 Disponible Variations in the accuracy of gravity recovery due to ground track variability: GRACE, CHAMP, and GOCE / J. Klokocnik in Journal of geodesy, vol 82 n° 12 (December 2008)
[article]
Titre : Variations in the accuracy of gravity recovery due to ground track variability: GRACE, CHAMP, and GOCE Type de document : Article/Communication Auteurs : J. Klokocnik, Auteur ; C.A. Wagner, Auteur ; J. Kostelecky, Auteur ; et al., Auteur Année de publication : 2008 Article en page(s) : pp 917 - 927 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] GOCE
[Termes IGN] GRACE
[Termes IGN] orbite
[Termes IGN] poursuite de satellite
[Termes IGN] précision des mesures
[Termes IGN] résonanceRésumé : (Auteur) Following an earlier recognition of degraded monthly geopotential recovery from GRACE (Gravity Recovery And Climate Experiment) due to prolonged passage through a short repeat (low order resonant) orbit, we extend these insights also to CHAMP (CHAllenging Minisatellite Payload) and GOCE (Gravity field and steady state Ocean Circulation Explorer). We show wide track-density variations over time for these orbits in both latitude and longitude, and estimate that geopotential recovery will be as widely affected as well within all these regimes, with lesser track density leading to poorer recoveries. We then use recent models of atmospheric density to estimate the future orbit of GRACE and warn of degraded performance as other low order resonances are encountered in GRACE’s free fall. Finally implications for the GOCE orbit are discussed. Copyright Springer Numéro de notice : A2008-474 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-008-0222-0 En ligne : https://doi.org/10.1007/s00190-008-0222-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29543
in Journal of geodesy > vol 82 n° 12 (December 2008) . - pp 917 - 927[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-08111 RAB Revue Centre de documentation En réserve L003 Disponible 266-08112 RAB Revue Centre de documentation En réserve L003 Disponible 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)
[article]
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 océaniqueRésumé : (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
in Journal of geodesy > vol 82 n° 9 (September 2008) . - pp 569 - 583[article]Réservation
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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 A data-driven approach to local gravity field modelling using spherical radial basis functions / R. Klees in Journal of geodesy, vol 82 n° 8 (August 2008)
[article]
Titre : A data-driven approach to local gravity field modelling using spherical radial basis functions Type de document : Article/Communication Auteurs : R. Klees, Auteur ; Robert Tenzer, Auteur ; I. Prutkin, Auteur ; Tobias Wittwer, Auteur Année de publication : 2008 Article en page(s) : pp 457 - 471 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] anomalie de pesanteur
[Termes IGN] champ de pesanteur local
[Termes IGN] fonction de base radiale
[Termes IGN] hauteur ellipsoïdale
[Termes IGN] nivellement par GPS
[Termes IGN] Pays-Bas
[Termes IGN] problème des valeurs limitesRésumé : (Auteur) We propose a methodology for local gravity field modelling from gravity data using spherical radial basis functions. The methodology comprises two steps: in step 1, gravity data (gravity anomalies and/or gravity disturbances) are used to estimate the disturbing potential using least-squares techniques. The latter is represented as a linear combination of spherical radial basis functions (SRBFs). A data-adaptive strategy is used to select the optimal number, location, and depths of the SRBFs using generalized cross validation. Variance component estimation is used to determine the optimal regularization parameter and to properly weight the different data sets. In the second step, the gravimetric height anomalies are combined with observed differences between global positioning system (GPS) ellipsoidal heights and normal heights. The data combination is written as the solution of a Cauchy boundary-value problem for the Laplace equation. This allows removal of the non-uniqueness of the problem of local gravity field modelling from terrestrial gravity data. At the same time, existing systematic distortions in the gravimetric and geometric height anomalies are also absorbed into the combination. The approach is used to compute a height reference surface for the Netherlands. The solution is compared with NLGEO2004, the official Dutch height reference surface, which has been computed using the same data but a Stokes-based approach with kernel modification and a geometric six-parameter “corrector surface” to fit the gravimetric solution to the GPS-levelling points. A direct comparison of both height reference surfaces shows an RMS difference of 0.6 cm; the maximum difference is 2.1 cm. A test at independent GPS-levelling control points, confirms that our solution is in no way inferior to NLGEO2004. Copyright Springer Numéro de notice : A2008-319 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-007-0196-3 En ligne : https://doi.org/10.1007/s00190-007-0196-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29312
in Journal of geodesy > vol 82 n° 8 (August 2008) . - pp 457 - 471[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-08071 RAB Revue Centre de documentation En réserve L003 Disponible 266-08072 RAB Revue Centre de documentation En réserve L003 Disponible Rotational bulge and one plume convection pattern: Influence on Martian true polar wander [short paper] / Hélène Rouby in Earth and planetary science letters, vol 272 n° 1-2 (30 July 2008)
[article]
Titre : Rotational bulge and one plume convection pattern: Influence on Martian true polar wander [short paper] Type de document : Article/Communication Auteurs : Hélène Rouby , Auteur ; Marianne Greff-Lefftz, Auteur ; Jean Besse, Auteur Année de publication : 2008 Article en page(s) : pp 212 - 220 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Mars (planète)
[Termes IGN] mouvement du pôle
[Termes IGN] Rotation de planèteRésumé : (auteur) Motion of the entire solid planet with respect to its spin axis have been proposed on Mars. This movement is known as True Polar Wander (TPW). According to the conservation of angular momentum with no external torque, on geological time scales the axis of maximum inertia of a planet is aligned with the rotation axis. Then rearrangement of masses within the mantle disturbs the planet's inertia and induces TPW. The convection pattern on Mars is possibly controlled by a sequence of single plumes originating from the core-mantle boundary. Using a homogeneous model of the martian mantle and modelling the plume as a sphere, we calculate the inertial tensor perturbations caused by the plume mass anomaly. We investigate the stabilizing influence of the remnant rotational bulge due to the lithosphere elasticity on these perturbations. It appears that, during early martian history, the elastic lithosphere was thin enough to allow its fractures under the inertia perturbations induced by a hot plume. Consequently, the lithosphere's behaviour became effectively viscoelastic and the plume could induce large TPW. We conclude that one plume convection pattern should have greatly influenced the rotation pole behaviour during early Mars history: around 4 Gyr ago, Mars already could have experienced two TPW events lasting possibly only a few million years each. We then compare our scenario with others already published in the literature. Numéro de notice : A2008-637 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.epsl.2008.04.044 En ligne : https://doi.org/10.1016/j.epsl.2008.04.044 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103442
in Earth and planetary science letters > vol 272 n° 1-2 (30 July 2008) . - pp 212 - 220[article]Retrieving earthquake signature in GRACE gravity solutions / Olivier de Viron in Geophysical journal international, vol 174 n° 1 (July 2008)PermalinkGeoid, sea level and vertical datum of the Arctic improved by ICESAT and GRACE / Henriette Skourup in Geomatica, vol 62 n° 2 (June 2008)PermalinkInteractions terre-atmosphère et rotation de la terre / Olivier de Viron in Géomatique expert, n° 63 (01/06/2008)PermalinkMulti-technique monitoring of ocean tide loading in Northern France / Muriel Llubes in Comptes rendus : Géoscience, vol 340 n° 6 (June 2010)PermalinkOcean tide loading (OTL) displacements from global and local grids: comparisons to GPS estimates over the shelf of Brittany, France / Stavros A. Melachroinos in Journal of geodesy, vol 82 n° 6 (June 2008)PermalinkGPS estimates of ocean tide loading in NW-France: Determination of ocean tide loading constituents and comparison with a recent ocean tide model / Mathilde Vergnolle in Geophysical journal international, vol 173 n° 2 (May 2008)PermalinkTerrestrial reference frame implementation in global GPS analysis at TIGA ULR consortium / Guy Wöppelmann in Physics and chemistry of the Earth (A/B/C), vol 33 n° 3-4 ([01/05/2008])PermalinkAstronomical-topographic levelling using high-precision astrogeodetic vertical deflections and Digital Terrain Model data / C. Hirt in Journal of geodesy, vol 82 n° 4-5 (April - May 2008)PermalinkLength-of-day and space-geodetic determination of the Earth's variable gravity field / G. Bourda in Journal of geodesy, vol 82 n° 4-5 (April - May 2008)PermalinkTransforming ellipsoidal heights and geoid undulations between different geodetic reference frames / Christopher Kotsakis in Journal of geodesy, vol 82 n° 4-5 (April - May 2008)Permalink