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Termes IGN > sciences naturelles > sciences de la Terre et de l'univers > géosciences > géophysique interne > géodésie > géodésie spatiale > interférométrie > interférométrie à très grande base > données ITGB
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New trends for the realization of the international terrestrial reference system / Zuheir Altamimi in Advances in space research, vol 30 n° 2 (July 2002)
[article]
Titre : New trends for the realization of the international terrestrial reference system Type de document : Article/Communication Auteurs : Zuheir Altamimi , Auteur ; Claude Boucher , Auteur ; Patrick Sillard , Auteur Année de publication : 2002 Article en page(s) : 9 p. ; pp 175 - 184 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] données GNSS
[Termes IGN] données GPS
[Termes IGN] données ITGB
[Termes IGN] géodésie spatiale
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] International Terrestrial Reference SystemRésumé : (Auteur) With the advent of Space geodesy techniques in early eighties, global terrestrial reference frames became available whose precision is still improving parallel to measuring and modeling advances. As a global reference, the realization of the International Terrestrial Reference System (ITRS), known as the International Terrestrial Reference Frame (ITRF), maintained by the International Earth Rotation Service, has sustained substantial improvement and enhancement. One of the major new trends is the 2000 ITRS realization, to be considered as a standard solution for a wide user community (geodesy, geophysics, astronomy, etc.). The ITRF2000 comprises on one hand primary core stations observed by VLBI, LLR, GPS, SLR and DORIS techniques and, on the other hand, significant extension provided by regional GPS networks for densifications as well as other useful geodetic markers tied to space geodetic ones. The ITRF2000 combination and implementation strategy are described in this paper. Important results in terms of datum definition as well as quality assessment of the ITRF2000 are presented. Numéro de notice : 10524 Affiliation des auteurs : LAREG (1991-2011) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/S0273-1177(02)00282-X Date de publication en ligne : 22/08/2002 En ligne : https://doi.org/10.1016/S0273-1177(02)00282-X Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=33430
in Advances in space research > vol 30 n° 2 (July 2002) . - 9 p. ; pp 175 - 184[article]On the Unification of Indonesian Local Height Systems / Khafid (1998)
Titre : On the Unification of Indonesian Local Height Systems Type de document : Thèse/HDR Auteurs : Khafid, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 1998 Collection : DGK - C Sous-collection : Dissertationen num. 488 Importance : 110 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-9528-1 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] archipel
[Termes IGN] données altimétriques
[Termes IGN] données GPS
[Termes IGN] données ITGB
[Termes IGN] Earth Gravity Model 1996
[Termes IGN] harmonique sphérique
[Termes IGN] Indonésie
[Termes IGN] Java (île de)
[Termes IGN] niveau moyen des mers
[Termes IGN] problème des valeurs limites
[Termes IGN] réseau altimétrique local
[Termes IGN] Sumatra
[Termes IGN] système de référence altimétriqueIndex. décimale : 30.10 Systèmes de référence et réseaux géodésiques Résumé : (Auteur) Height systems are usually referred to the mean sea level at tide gauges. Due to the deviation of mean sea level from one equipotential surface of the Earth's gravity field, the geoid, off-sets exist between the various height systems. These off-sets also affect derived quantities such as gravity anomalies. As long as the direct determination of the potential difference between two datum points, by geodetic levelling and gravimetry , is possible the connection, i.e. unification, of height systems is straightforward. It is a serious problem, however, whenever height datum zones are disconnected by sea. With the advent of advanced space positioning techniques and satellite altimetry new solution strategies for the worldwide unification of height systems came into discussion. This investigation deals with the regional unification of height systems for the area of the Indonesian archipelago.
It is a well-known fact that height datum unification is a global problem. However under certain circumstances it is possible to restrict the unification to a certain part of the Earth. Solution strategies make use of a land, a sea and an integrated component. The sea approach is based on satellite altimetry and oceanic levelling, the land approach on space positioning and spirit levelling, including tide gauge registrations. The link between both components is the solution of the geodetic boundary value problem applied regionally, with the aim to provide potential differences between the various vertical datum systems.
The five fundamental elements related to unification of height systems are investigated individually. Mean sea surface heights are determined by satellite radar altimetry, precise orbit ephemerides and corrections for tides and mesoscale ocean variations. By applying collinear pass analysis, crossover adjustment and a least-squares fit to the TOPEX/POSEIDON (T/P) mean sea surface, the mean sea surface in Indonesian waters is determined using the combined altimetry data from the missions Geosat/ERM, ERS-1/35 days, and T/P with an estimated accuracy of 10 cm. The high resolution data set of the ERS-1/168 days repeat mission has been processed with a simplified procedure. The result is consistent with that of the combination solution. As second element sea surface topography is derived from ocean levelling employing hydrographic data. The sea surface topography for Indonesian waters, especially in the eastern Indonesian region, is computed using several oceanographic data sets, the spherical harmonic model of the old Levitus data set up to degree and order 36, data from the Snellius-I and II expeditions, and the recent data set of the World Ocean Atlas 1994. The accuracy of ocean levelling depends on the measurement errors, data sampling and the reference surface. The assumption of a level of no motion at a certain depth, in this investigation 2000 dB is required to eliminate a fundamental indeterminancy. It is a problematic assumption. Further improvement will be possible once better data coverage and higher accuracy measurements are available. To increase the accuracy of local height datum connection, as third element the relative geoid computation is investigated. The relative geoid computation with inclusion of the height off-sets as unknowns should be the appropriate strategy for the solution of height datum connection over small distances between computation points. Finally as fourth and fifth element, the levelling network and the possibility of geodetic space techniques (GPS and VLBI) for height datum connection in Indonesia are reviewed. The levelling networks of Sumatra, Java, Kalimantan, Bali, Lombok, Sulawesi East Timor, Maluku, Seram have been extended by BAKOSURTANAL in recent years. A geodynamic GPS network is under development in the context of the GEODYSSEA project. They offer a promising prospect for use in a precise regional vertical datum connection. From the comparison of sea surface topography as derived from steric levelling and from altimetry and a spherical harmonic geoid model (EGM96) up to degree and order 360, it can be concluded that sea surface topography as computed from the World Ocean Atlas 1994 can be used for preliminary Indonesian height datum connections. The sea surface topography in the South-West coast of Sumatra is about -16 cm, in the South coast of Java it increases from -14 cm (west) to -8 cm (east).Numéro de notice : 28005 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=63352 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 28005-01 30.10 Livre Centre de documentation Géodésie Disponible 28005-02 30.10 Livre Centre de documentation Géodésie Disponible Untersuchungen zu Erddeformationsmodellen für die Auswertung von geodätischen VLBI-Messungen / Rüdiger Haas (1996)
Titre : Untersuchungen zu Erddeformationsmodellen für die Auswertung von geodätischen VLBI-Messungen Titre original : [Recherches sur les modèles de déformation de la terre pour l'utilisation des mesures géodésiques d'interférométrie de très longue base] Type de document : Thèse/HDR Auteurs : Rüdiger Haas, Auteur Editeur : Francfort sur le Main : Institut für Angewandte Geodäsie Année de publication : 1996 Collection : DGK - C Sous-collection : Dissertationen num. 466 Importance : 103 p. Format : 21 x 30 cm Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse comparative
[Termes IGN] déformation de la croute terrestre
[Termes IGN] données ITGB
[Termes IGN] interférométrie à très grande base
[Termes IGN] marée terrestre
[Termes IGN] résonance
[Termes IGN] rotation de la Terre
[Termes IGN] surcharge atmosphérique
[Termes IGN] surcharge océaniqueIndex. décimale : 30.63 Télémétrie laser sur satellite, Télémétrie laser sur lune, VLBI Résumé : (Auteur) Within the last 20 years geodetic Very Long Baseline Interferometry [VLBI] has been developed as an important technique for geodesy and geophysics. The primary purpose of geodetic VLBI is the establishment of terrestrial and celestial reference frames, measurement of present day tectonic motion and monitoring of Earth rotation.
The accuracy in modeling the theoretical observations for the analysis of space geodetic measurements should ideally be higher than the instrumental precision. Latter is for today's VLBI-system in the millimeter range while the accuracy of modeling is in the centimeter range.
For this reason international efforts endeavor to raise the accuracy of modeling to the millimeter level. As part of this effort this thesis investigates the modeling of Earth deformation effects for the analysis of geodetic VLBI observations. Existing theoretical models for Earth tides, ocean loading and atmospheric loading and their actual application in the analysis of VLBI data are considered.
In a first step worst case simulations are computed in order to evaluate the magnitude of the effects when neglecting them in the analysis.
Then parameters of the Earth deformation models are estimated from VLBI data to test the sensitivity of the VLBI observations to these neglections. In the results the theoretically predicted resonance of the Earth tides is clearly visible. However, the empirical resonance period is significantly different from the theoretical one with a tendency towards an independently inferred value from gravimetry. The estimates for ocean loading show a tendency towards the values of a newly developed loading model. Estimates for atmospheric loading show good agreement with theoretical values. Based upon these considerations recommendations for the treatment of Earth deformation effects in the analysis of space geodetic observations are developed.
As a consequence the VLBI analysis software is extended following these recommendations. The results of these extensions are tested in the analysis of VLBI observations in three different VLBI networks. Results for baseline lengths and Earth rotation parameters are compared with the results that are achieved using the standard analysis software. The comparisons show, that short time and long time repeatability of baseline length measurements improves with the use of the extended analysis software. The accuracy of Earth rotation parameters can be improved, too. The use of the extended software removes diurnal and sub diurnal parts from high frequency Earth rotation parameters, which have been misinterpreted as Earth rotation variations.Numéro de notice : 27066 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=56315 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 27066-01 30.63 Livre Centre de documentation Géodésie Disponible Detection of atmospheric pressure loading using very long baseline interferometry measurements / Tonie M. VanDam in Journal of geophysical research : Solid Earth, vol 99 n° 3 (10/03/1994)
[article]
Titre : Detection of atmospheric pressure loading using very long baseline interferometry measurements Type de document : Article/Communication Auteurs : Tonie M. VanDam, Auteur Année de publication : 1994 Article en page(s) : pp 4505 - 4517 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] correction atmosphérique
[Termes IGN] données ITGB
[Termes IGN] fonction de Green
[Termes IGN] géodésie physique
[Termes IGN] pression atmosphérique
[Termes IGN] surcharge atmosphériqueRésumé : (Auteur) Loading of the Earth by the temporal redistribution of global atmospheric mass is likely to displace the positions of geodetic monuments by tens of millimeters both vertically and horizontally. Estimates of these displacements are determined by convolving National Meteorological Center (NMC) global values of atmospheric surface pressure with Farrell's elastic Green's functions. An analysis of the distances between radio telescopes determined by very long baseline interferometry (VLBI) between 1984 and 1992 reveals that in many of the cases studied there is a significant contribution to baseline length change due to atmospheric pressure loading. Our analysis covers intersite distances of between 1000 and 10,000 km and is restricted to those baselines measured more than 100 times. Numéro de notice : A1994-020 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1029/93JB02758 Date de publication en ligne : 14/03/1994 En ligne : https://doi.org/10.1029/93JB02758 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=25724
in Journal of geophysical research : Solid Earth > vol 99 n° 3 (10/03/1994) . - pp 4505 - 4517[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 194-94031 Revue Centre de documentation Indéterminé Disponible Optimierung von Beobachtungsplänen in der Langbasisinterferometrie (VLBI) / H. Steufmehl (1994)
Titre : Optimierung von Beobachtungsplänen in der Langbasisinterferometrie (VLBI) Titre original : [Optimisation de la prévision des observations d'interférométrie à très grande base] Type de document : Thèse/HDR Auteurs : H. Steufmehl, Auteur Editeur : Francfort sur le Main : Institut für Angewandte Geodäsie Année de publication : 1994 Collection : DGK - C Sous-collection : Dissertationen num. 406 Importance : 75 p. Format : 21 x 30 cm Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] données ITGB
[Termes IGN] interférométrie à très grande base
[Termes IGN] matrice de covariance
[Termes IGN] optimisation (mathématiques)
[Termes IGN] programmation dynamiqueIndex. décimale : 30.63 Télémétrie laser sur satellite, Télémétrie laser sur lune, VLBI Résumé : (Auteur)Very Long Baseline Interferomerty (VLBI) is a method, which makes use of the radiation of extragalactical radio sources received by radio telescopes. The time difference between the arrival of the signals at two different observing stations is the prime VLBI-observable.
When several radio telescopes are linked to a network and have observed different sources for a time interval of normally 24 hours, we speak of a VLBI experiment. The sequence of the sources to be monitored is deter-mined by the observing schedule.
In order to obtain the best quality of determination of the target parameters, the variance/covariance matrix of the parameters should have an optimal design. This optimal design depends on the geometric configuration of the observations. Until now, the observations are selected interactively in a time-consuming process and without a precise knowledge of the quality of determination. In this thesis an algorithm is developed which allows the automatic creation of optimized VLBI observing schedules.
The analogies between the optimization of geodetic networks and the problem under consideration are dis-cussed and then the problem is presented as a 1 .order design problem where the observing stations must be linked optimally by time delay observations. It is a problem of sequentiel decisions, which can be solved on the basis of the process of dynamic optimization. The problem is analysed and a simplified numerical method of
solution suited for implementation in a computer program is derived.
i
Furthermore, simulated observing schedules from the international observing program IRIS are presented. Some of those schedules have been used in real measurement campaigns. The observing positions have a tendency to accumulate in certain regions of the observable sky. The improvements of the accuracies range between 15% to 20% in comparison to the 'hand-made' schedules.
The significance of the new method is given on the one hand by the various possibilities of application while designing new networks and schedules and on the other hand by the much more efficient way of creating obser-ving schedules.Numéro de notice : 28077 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=63424 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 28077-01 30.63 Livre Centre de documentation Géodésie Disponible Einflüsse der Quellenstruktur in der Praxis der geodätischen VLBI / G. Zeppenfeld (1993)PermalinkData analysis of geodetic VLBI organized by the communications research laboratory / T. Kondo (1992)PermalinkOrientation de la terre par mesure VLBI / Anne-Marie Gontier (1992)PermalinkA parametrized solid Earth tide model and ocean tide loading effects for global geodetic baseline measurements / H. Scherneck in Geophysical journal international, vol 106 n° 3 (September 1991)PermalinkAnalyse von Lasermessungen zum Mond im Rahmen einer post-Newton'schen Theorie / J. Muller (1991)PermalinkRadiointerferometrische Beobachtungen zur Bestimmung der Polbewegung unter Benutzung langer Nord-Süd-Basislinien / Axel Nothnagel (1991)PermalinkA method to enhance the cross correlation of millisecond pulsars VLBI data observations of PSR1937+214 / J.F. Lestrade (1990)PermalinkStructure des sources radio extragalactiques dans les observations VLBI d'astrométrie et de géodynamique / Patrick Charlot (1989)PermalinkComparaison et combinaison des jeux de coordonnées provenant de diverses techniques de géodésie spatiale (VLBI, Laser, Doppler, GPS) / C. Ndao (1987)PermalinkDie Radiointerferometrie auf langen Basen zur Bestimmung von Punktverschiebungen und Erdrotationsparametern / Harald Schuh (1987)Permalink