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Evaluation of the GSRM2.1 and the NUVEL1-A values in Europe using SLR and VLBI based geodetic velocity fields / Mina Rahmani in Survey review, vol 54 n° 385 (July 2022)  

Public [article]  inSurvey review > vol 54 n° 385 (July 2022) . - pp 349 - 362 Titre : Evaluation of the GSRM2.1 and the NUVEL1-A values in Europe using SLR and VLBI based geodetic velocity fields Type de document : Article/Communication Auteurs : Mina Rahmani, Auteur ; Vahab Nafisi, Auteur ; Sigrid Böhm, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : pp 349 - 362 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] analyse comparative [Termes IGN] champ de vitesse [Termes IGN] cohérence des données [Termes IGN] données ITGB [Termes IGN] données TLS (télémétrie) [Termes IGN] magnitude [Termes IGN] tectonique des plaques Résumé : (auteur) The NUVEL1-A is one of the old and popular plate tectonic models. While the NUVEL1-A is a geological-based model, recently a model has been proposed (GSRM2.1 model) which is based on the results of space geodetic techniques. In this work, we investigate the consistency of these models with the VLBI and SLR results in Europe. Direction and magnitude of the horizontal motion from NUVEL-1A and GSRM2.1 models are compared with corresponding values from both geodetic techniques. This comparison provides valuable deductions such as: (1) The values of geodetic-based model (GSRM2.1) show better agreement with SLR and VLBI results (2) In each comparison between geodetic results and modelled values, direction divergence is larger than magnitude difference. Numéro de notice : A2022-536 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2021.1943633 Date de publication en ligne : 25/06/2021 En ligne : https://doi.org/10.1080/00396265.2021.1943633 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101092 [article]

Baseline-dependent clock offsets in VLBI data analysis / Hana Krásná in Journal of geodesy, vol 95 n° 12 (December 2021)  

Public [article]  inJournal of geodesy > vol 95 n° 12 (December 2021) . - n° 126 Titre : Baseline-dependent clock offsets in VLBI data analysis Type de document : Article/Communication Auteurs : Hana Krásná, Auteur ; Frédéric Jaron, Auteur ; Jacob Gruber, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 126 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] bande S [Termes IGN] décalage d'horloge [Termes IGN] données ITGB [Termes IGN] horloge atomique [Termes IGN] interférométrie à très grande base [Termes IGN] ligne de base [Termes IGN] paramètres d'orientation de la Terre [Termes IGN] retard ionosphèrique Résumé : (auteur) The primary goal of the geodetic Very Long Baseline Interferometry (VLBI) technique is to provide highly accurate terrestrial and celestial reference frames as well as Earth orientation parameters. In compliance with the concept of VLBI, additional parameters reflecting relative offsets and variations of the atomic clocks of the radio telescopes have to be estimated. In addition, reality shows that in many cases significant offsets appear in the observed group delays for individual baselines which have to be compensated for by estimating so-called baseline-dependent clock offsets (BCOs). For the first time, we systematically investigate the impact of BCOs to stress their importance for all kinds of VLBI data analyses. For our investigations, we concentrate on analyzing data from both legacy networks of the CONT17 campaign. Various aspects of BCOs including their impact on the estimates of geodetically important parameters, such as station coordinates and Earth orientation parameters, are investigated. In addition, some of the theory behind the BCO determination, e.g., the impact of changing the reference clock in the observing network on the BCO estimate is introduced together with the relationship between BCOs and triangle delay closures. In conclusion, missing channels, and here in particular at S band, affecting the ionospheric delay calibration, are identified to be the dominant cause for the occurrence of significant BCOs in VLBI data analysis. Numéro de notice : A2021-815 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01579-5 Date de publication en ligne : 01/11/2021 En ligne : https://doi.org/10.1007/s00190-021-01579-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98896 [article]

Observable quality assessment of broadband very long baseline interferometry system / Ming H. Xu in Journal of geodesy, vol 95 n° 5 (May 2021)  

Public [article]  inJournal of geodesy > vol 95 n° 5 (May 2021) . - n° 51 Titre : Observable quality assessment of broadband very long baseline interferometry system Type de document : Article/Communication Auteurs : Ming H. Xu, Auteur ; James M. Anderson, Auteur ; Robert Heinkelmann, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 51 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] données VGOS [Termes IGN] erreur moyenne quadratique [Termes IGN] interférométrie à très grande base [Termes IGN] pondération [Termes IGN] propagation ionosphérique [Termes IGN] retard ionosphèrique [Termes IGN] teneur totale en électrons Résumé : (auteur) The next-generation, broadband geodetic very long baseline interferometry system, named VGOS, is developing its global network, and VGOS networks with a small size of 3–7 stations have already made broadband observations from 2017 to 2019. We made quality assessments for two kinds of observables in the 21 VGOS sessions currently available: group delay and differential total electron content (δTEC). Our study reveals that the random measurement noise of VGOS group delays is at the level of less than 2 ps (1ps=10−12 s), while the contributions from systematic error sources, mainly source structure related, are at the level of 20 ps. Due to the significant improvement in measurement noise, source structure effects with relatively small magnitudes that are not overwhelming in the S/X VLBI system, for instance 10 ps, are clearly visible in VGOS observations. Another critical error source in VGOS observations is discrete delay jumps, for instance, a systematic offset of about 310 ps or integer multiples of that. The predominant causative factor is found to be related to source structure. The measurement noise level of δTEC observables is about 0.07 TECU, but the systematic effects are five times larger than that. A strong correlation between group delay and δTEC observables is discovered with a trend of 40 ps/TECU for observations with large structure effects; there is a second trend in the range 60–70 ps/TECU when the measurement noise is dominant. Numéro de notice : A2021-346 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01496-7 Date de publication en ligne : 13/04/2021 En ligne : https://doi.org/10.1007/s00190-021-01496-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97590 [article]

Benefits of non-tidal loading applied at distinct levels in VLBI analysis / Matthias Glomsda in Journal of geodesy, vol 94 n° 9 (September 2020)  

Public [article]  inJournal of geodesy > vol 94 n° 9 (September 2020) . - n° 90 Titre : Benefits of non-tidal loading applied at distinct levels in VLBI analysis Type de document : Article/Communication Auteurs : Matthias Glomsda, Auteur ; Mathis Blossfeld, Auteur ; Manuela Seitz, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : n° 90 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] données ITGB [Termes IGN] effet de charge [Termes IGN] interférométrie à très grande base [Termes IGN] pesanteur hors marée [Termes IGN] retard troposphérique [Termes IGN] série temporelle [Termes IGN] surcharge hydrologique [Termes IGN] surcharge océanique [Termes IGN] transformation de Helmert Résumé : (auteur) In the analysis of very long baseline interferometry (VLBI) observations, many geophysical models are used for correcting the theoretical signal delay. In addition to the conventional models described by Petit and Luzum (eds) (IERS Conventions, 2010), we are applying different parts of non-tidal site loading, namely the atmospheric, oceanic, and hydrological ones. To investigate their individual contributions, these parts are considered both separately and combined to a total loading. The application of the corresponding site displacements is performed at two distinct levels of the geodetic parameter estimation process (observation and normal equation level), which turn out to give very similar results in many cases. To validate our findings internally, the site displacements are provided by two different data centres: the Earth-System-Modelling group at the Deutsches GeoForschungsZentrum in Potsdam (ESMGFZ, see Dill and Dobslaw, J Geophys Res Solid Earth, 2013. https://doi.org/10.1002/jgrb.50353ISTEX)] and the International Mass Loading Service [IMLS, see Petrov (The international mass loading service, 2015)]. We show that considering non-tidal loading is actually useful for mitigating systematic effects in the VLBI results, like annual signals in the station height time series. If the sum of all non-tidal loading parts is considered, the WRMS of the station heights and baseline lengths is reduced in 80–90% of all cases, and the relative improvement is about −3.5% on average. The main differences between our chosen providers originate from hydrological loading. Numéro de notice : A2020-540 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01418-z Date de publication en ligne : 31/08/2020 En ligne : https://doi.org/10.1007/s00190-020-01418-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95741 [article]

GipsyX/RTGx, a new tool set for space geodetic operations and research / Willy I. Bertiger in Advances in space research, vol 66 n° 3 (1 August 2020)  

Public [article]  inAdvances in space research > vol 66 n° 3 (1 August 2020) . - pp 469 - 489 Titre : GipsyX/RTGx, a new tool set for space geodetic operations and research Type de document : Article/Communication Auteurs : Willy I. Bertiger, Auteur ; Yoaz E. Bar-Sever, Auteur ; A. Dorsey, Auteur ; Bruce J. Haines, Auteur ; N.R. Harvey, Auteur ; Dan Hemberger, Auteur ; Michael B. Heflin, Auteur ; Wenwen Lu, Auteur ; Mark Miller, Auteur ; Angelyn Moore, Auteur ; Dave Murphy, Auteur ; Paul Ries, Auteur ; L.J. Romans, Auteur ; Aurore E. Sibois, Auteur ; Ant Sibthorpe, Auteur ; Bela Szilagyi, Auteur ; Michele Vallisneri, Auteur ; Pascal Willis , Auteur Année de publication : 2020 Projets : 3-projet - voir note / Article en page(s) : pp 469 - 489 Note générale : bibliographie The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] données DORIS [Termes IGN] données GNSS [Termes IGN] données ITGB [Termes IGN] données TLS (télémétrie) [Termes IGN] filtre de Kalman [Termes IGN] horloge atomique [Termes IGN] horloge du satellite [Termes IGN] logiciel d'orbitographie [Termes IGN] positionnement ponctuel précis [Termes IGN] série temporelle [Termes IGN] temps réel [Termes IGN] traitement de données GNSS Résumé : (auteur) GipsyX/RTGx is the Jet Propulsion Laboratory’s (JPL) next generation software package for positioning, navigation, timing, and Earth science using measurements from three geodetic techniques: Global Navigation Satellite Systems (GNSS), Satellite Laser Ranging (SLR), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS); with Very Long Baseline Interferometry (VLBI) under development. The software facilitates combined estimation of geodetic and geophysical parameters using a Kalman filter approach on real or simulated data in both post-processing and in real-time. The estimated parameters include station coordinates and velocities, satellite orbits and clocks, Earth orientation, ionospheric and tropospheric delays. The software is also capable of full realization of a dynamic terrestrial reference through analysis and combination of time series of ground station coordinates. Applying lessons learned from its predecessors, GIPSY-OASIS and Real Time GIPSY (RTG), GipsyX/RTGx was re-designed from the ground up to offer improved precision, accuracy, usability, and operational flexibility. We present some key aspects of its new architecture, and describe some of its major applications, including Real-time orbit determination and ephemeris predictions in the U.S. Air Force Next Generation GPS Operational Control Segment (OCX), as well as in JPL’s Global Differential GPS (GDGPS) System, supporting User Range Error (URE) of 5 cm RMS; precision post-processing GNSS orbit determination, including JPL’s contributions to the International GNSS Service (IGS) with URE in the 2 cm RMS range; Precise point positioning (PPP) with ambiguity resolution, both statically and kinematically, for geodetic applications with 2 mm horizontal, and 6.5 mm vertical repeatability for static positioning; Operational orbit and clock determination for Low Earth Orbiting (LEO) satellites, such as NASA’s Gravity Recovery and Climate Experiment (GRACE) mission with GRACE relative clock alignment at the 20 ps level; calibration of radio occultation data from LEO satellites for weather forecasting and climate studies; Satellite Laser Ranging (SLR) to GNSS and LEO satellites, DORIS-based and multi-technique orbit determination for LEO; production of terrestrial reference frames and Earth rotation parameters in support of JPL’s contribution to the International Terrestrial Reference Frame (ITRF). Numéro de notice : A2020-575 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : INFORMATIQUE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2020.04.015 Date de publication en ligne : 22/04/2020 En ligne : https://doi.org/10.1016/j.asr.2020.04.015 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96369 [article]

Geodetic VLBI for precise orbit determination of Earth satellites: a simulation study / Grzegorz Klopotek in Journal of geodesy, vol 94 n° 6 (June 2020)  

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Combinatorial optimization applied to VLBI scheduling / A. Corbin in Journal of geodesy, vol 94 n°2 (February 2020)  

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Least-squares cross-wavelet analysis and its applications in geophysical time series / Ebrahim Ghaderpour in Journal of geodesy, vol 92 n° 10 (October 2018)  

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Basic Earth's Parameters as estimated from VLBI observations / Ping Zhu in Geodesy and Geodynamics, vol 8 n° 6 (November 2017)  

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Application of ray-traced tropospheric slant delays to geodetic VLBI analysis / Armin Hofmeister in Journal of geodesy, vol 91 n° 8 (August 2017)  

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A global terrestrial reference frame from simulated VLBI and SLR data in view of GGOS / Susanne Glaser in Journal of geodesy, vol 91 n° 7 (July 2017)  

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The extension of the parametrization of the radio source coordinates in geodetic VLBI and its impact on the time series analysis / Maria Karbon in Journal of geodesy, vol 91 n° 7 (July 2017)  

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Testing impact of the strategy of VLBI data analysis on the estimation of Earth Orientation Parameters and station coordinates / Agata Wielgosz in Reports on geodesy and geoinformatics, vol 101 (June 2016)  

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Caractérisation des signaux et des bruits des séries temporelles du géocentre et des paramètres de rotation de la Terre (EOP) / Bachir Gourine in Bulletin des sciences géographiques, n° 30 (2015 - 2016)

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The Fresnel–Fizeau effect and the atmospheric time delay in geodetic VLBI / S. M. Kopeikin in Journal of geodesy, vol 89 n° 8 (August 2015)  

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