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Systematic errors in the Z-geocenter derived using satellite tracking data: a case study from SPOT-4 DORIS data in 1998 / Pascal Willis in Journal of geodesy, vol 79 n° 10-11 (February 2006)  

Public [article]  inJournal of geodesy > vol 79 n° 10-11 (February 2006) . - pp 567 - 572 Titre : Systematic errors in the Z-geocenter derived using satellite tracking data: a case study from SPOT-4 DORIS data in 1998 Type de document : Article/Communication Auteurs : Pascal Willis , Auteur ; Jean-Paul Berthias, Auteur ; Yoaz E. Bar-Sever, Auteur Année de publication : 2006 Article en page(s) : pp 567 - 572 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] données DORIS [Termes IGN] erreur systématique [Termes IGN] géocentre [Termes IGN] orbitographie [Termes IGN] positionnement par DORIS [Termes IGN] poursuite de satellite Résumé : (Auteur) Within the scope of the Global Geodetic Observing System, Doppler Orbit Determination and Radiopositioning Integrated by Satellite - as a geodetic technique - can provide precise and continuous monitoring of the geocenter motion related to mass redistribution in the Earth, ocean and atmosphere system. We have reanalyzed 1998 DORIS/SPOT-4 (Satellite pour l'Observation de la Terre) data that were previously generating inconsistent geocenter positions (-65 cm offset). We show here that this error is due to an incorrect phase center correction provided with the DORIS preprocessed data resulting from a +12cm offset in the cross-track direction that has been confirmed since. We also conclude that a 1 mm error in the cross-track offset of non-yawing sun-synchronous SPOT satellites will generate a -6.5 mm error in the derived Z-geocenter. Other non-yawing satellites would also be affected by a similar effect whose amplitude could be easily estimated from the orbit inclination. Numéro de notice : A2006-086 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-005-0013-9 En ligne : https://doi.org/10.1007/s00190-005-0013-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27813 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-06012	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-06011	RAB	Revue	Centre de documentation	En réserve L003	Disponible

A strategy for determining the regional geoid by combining limited ground data with satellite-based global geopotential and topographical models: a case study of Iran / R. Kiamehr in Journal of geodesy, vol 79 n° 10-11 (February 2006)  

Public [article]  inJournal of geodesy > vol 79 n° 10-11 (February 2006) . - pp 602 - 612 Titre : A strategy for determining the regional geoid by combining limited ground data with satellite-based global geopotential and topographical models: a case study of Iran Type de document : Article/Communication Auteurs : R. Kiamehr, Auteur Année de publication : 2006 Article en page(s) : pp 602 - 612 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] anomalie de pesanteur [Termes IGN] données hétérogènes [Termes IGN] formule de Stokes [Termes IGN] géoïde gravimétrique [Termes IGN] géoïde local [Termes IGN] Iran [Termes IGN] méthode des moindres carrés [Termes IGN] MNS SRTM [Termes IGN] modèle numérique de terrain [Termes IGN] nivellement par GPS Résumé : (Auteur) The computation of regional gravimetric geoid models with reasonable accuracy, in developing countries, with sparse data is a difficult task that needs great care. Here, we investigate the procedure for gathering, evaluating and combining different data for the determination of a gravimetric geoid model for Iran, where limited ground gravity data are available. Heterogeneous data, including gravity anomalies, the high-resolution Shuttle Radar Topography Mission global digital terrain model and different global geopotential models including recently published Gravity Recovery and Climate Experiment models, are combined through least-squares modification of the Stokes formula. The new gravimetric geoid model, IRG04, agrees considerably better with GPS-levelling than any of the other recent local geoid model in the area. Its RMS fit with GPS-levelling is 0.27m and 3.8 ppm in the absolute and relative view, respectively. The relative accuracy of IRG04 is four times better than the most recently published global and regional geoid models available in this area. This progress shows the practical potential of the method of least-squares modification of Stokes's formula in combination with heterogeneous data for regional geoid determination. Numéro de notice : A2006-087 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-005-0009-5 En ligne : https://doi.org/10.1007/s00190-005-0009-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27814 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-06012	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-06011	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Multi-technique comparison of tropospheric zenith delays derived during the CONT02 campaign / Pascal Willis in Journal of geodesy, vol 79 n° 10-11 (February 2006)  

Public [article]  inJournal of geodesy > vol 79 n° 10-11 (February 2006) . - pp 613 - 623 Titre : Multi-technique comparison of tropospheric zenith delays derived during the CONT02 campaign Type de document : Article/Communication Auteurs : Pascal Willis , Auteur ; K. Snajdrova, Auteur ; Johannes Böhm , Auteur ; Rüdiger Haas, Auteur Année de publication : 2006 Article en page(s) : pp 613 - 623 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] analyse comparative [Termes IGN] distance zénithale [Termes IGN] données WVR [Termes IGN] écart type [Termes IGN] erreur systématique [Termes IGN] météorologie [Termes IGN] positionnement par DORIS [Termes IGN] positionnement par GPS [Termes IGN] prévision météorologique [Termes IGN] propagation troposphérique [Termes IGN] traitement du signal [Termes IGN] troposphère Résumé : (Auteur) In October 2002, 15 continuous days of Very Long Baseline Interferometry (VLBI) data were observed in the Continuous VLBI 2002 (CONT02) campaign. All eight radio telescopes involved in CONT02 were co-located with at least one other space-geodetic technique, and three of them also with a Water Vapor Radiometer (WVR). The goal of this paper is to compare the tropospheric zenith delays observed during CONT02 by VLBI, Global Positioning System (GPS), Doppler Orbitography Radiopositioning Integrated by Satellite (DORIS) and WVR and te, compare them also with operational pressure level data from the European Centre for Medium-Range Weather Forecasts (ECMWF). We show that the tropospheric zenith delays from VLBI and GPS are in good agreement at the 3-7 mm level. However, while only small biases can be found for most of the stations, at Kokee Park (Hawaii, USA) and Westford (Massachusetts, USA) the zenith delays derived by GPS are larger by more than 5 mm than those from VLBI. At three of the four DORIS stations, there is also a fairly good agreement with GPS and VLBI (about 10 mm), but at Kokee Park the agreement is only at about 30 mm standard deviation, probably due to the much older installation and type of DORIS equipment. This comparison also allows testing of different DORIS analysis strategies with respect to their real impact on the precision of the derived tropospheric parameters. Ground truth information about the zenith delays can also be obtained from the ECMWF numerical weather model and at three sites using WVR measurements, allowing for comparisons with results from the space-geodetic techniques. While there is a good agreement (with some problems mentioned above about DORIS) among the space-geodetic techniques, the comparison with WVR and ECMWF is at a lower accuracy level. The complete CONT02 data set is sufficient to derive a good estimate of the actual precision and accuracy of each geodetic technique for applications in meteorology. Numéro de notice : A2006-088 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-005-0010-z En ligne : https://doi.org/10.1007/s00190-005-0010-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27815 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-06012	RAB	Revue	Centre de documentation	En réserve L003	Disponible
266-06011	RAB	Revue	Centre de documentation	En réserve L003	Disponible