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Auteur Zuheir Altamimi
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Assessment of geocenter motion estimates from the IGS second reprocessing / Yifang Ma in GPS solutions, vol 24 n° 2 (April 2020)
[article]
Titre : Assessment of geocenter motion estimates from the IGS second reprocessing Type de document : Article/Communication Auteurs : Yifang Ma , Auteur ; Paul Rebischung , Auteur ; Zuheir Altamimi , Auteur ; Weiping Jiang, Auteur Année de publication : 2020 Projets : 3-projet - voir note / Article en page(s) : n° 55 Note générale : bibliographie
This study is supported by the National Science Fund for Distinguished Young Scholars (No. 41525014) and the National Key R&D Program of China (No. 2018YFC15036).Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] analyse comparative
[Termes IGN] données TLS (télémétrie)
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] mouvement du géocentre
[Termes IGN] série temporelle
[Termes IGN] variation saisonnière
[Termes IGN] variation temporelleRésumé : (auteur) We investigate geocenter motion time series derived from the combined solutions and six individual analysis center (AC) solutions of the International GNSS Service (IGS) second reprocessing campaign using the network shift approach, in terms of noise content, long-term trends, periodic and aperiodic variations. We assess these GNSS geocenter motion estimates by comparison with independent estimates from satellite laser ranging (SLR). The GNSS geocenter time series exhibit correlated noise which is better represented by a white plus power–law noise model in the X and Y directions, and by a white plus first-order autoregressive (or generalized Gauss–Markov) noise model in the Z direction. The GNSS geocenter time series include expected seasonal variations, but also spurious draconitic signals, particularly in the Z direction. GNSS annual geocenter motion estimates are in reasonable agreement with SLR estimates in the X and Y directions. In the Z direction, however, the annual signals derived from the IGS solutions disagree with SLR estimates, except for three particular ACs. This suggests that the different orbit modeling strategies used by these ACs may constitute an improvement over the conventional strategy employed by the other ACs. The background noise in GNSS and SLR geocenter time series finally appears to be correlated, suggesting that it might partly reflect real, aperiodic geocenter motion. Numéro de notice : A2020-838 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-020-0968-2 Date de publication en ligne : 10/03/2020 En ligne : https://doi.org/10.1007/s10291-020-0968-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98264
in GPS solutions > vol 24 n° 2 (April 2020) . - n° 55[article]Comparative analysis of different atmospheric surface pressure models and their impacts on daily ITRF2014 GNSS residual time series / Zhao Li in Journal of geodesy, vol 94 n°4 (April 2020)
[article]
Titre : Comparative analysis of different atmospheric surface pressure models and their impacts on daily ITRF2014 GNSS residual time series Type de document : Article/Communication Auteurs : Zhao Li, Auteur ; Chen Wu, Auteur ; Tonie M. van Dam, Auteur ; Paul Rebischung , Auteur ; Zuheir Altamimi , Auteur Année de publication : 2020 Projets : 3-projet - voir note / Article en page(s) : n° 42 Note générale : bibliographie
This research is supported by the National Key Research and Development Program of China (Project 2016YFB0502101), the European Commission/Research Grants Council (RGC) Collaboration Scheme sponsored by the Research Grants Council of Hong Kong Special Administrative Region, China (Project No. E-PolyU 501/16), and the National Science Foundation for Distinguished Young Scholars of China (Grant No. 41525014).Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] analyse comparative
[Termes IGN] coefficient de corrélation
[Termes IGN] données GNSS
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] MERRA
[Termes IGN] modèle atmosphérique
[Termes IGN] pression atmosphérique
[Termes IGN] radar JPL
[Termes IGN] résidu
[Termes IGN] série temporelle
[Termes IGN] station GNSSRésumé : (auteur) To remove atmospheric pressure loading (ATML) effect from GNSS coordinate time series, surface pressure (SP) models are required to predict the displacements. In this paper, we modeled the 3D ATML surface displacements using the latest MERRA-2 SP grids, together with four other products (NCEP-R-1, NCEP-R-2, ERA-Interim and MERRA) for 596 globally distributed GNSS stations, and compared them with ITRF2014 residual time series. The five sets of ATML displacements are highly consistent with each other, particularly for those stations far away from coasts, of which the lowest correlations in the Up component for all the four models w.r.t MERRA-2 become larger than 0.91. ERA-Interim-derived ATML displacement performs best in reducing scatter of the GNSS height for 90.3% of the stations (89.3% for NCEP-R-1, 89.1% for NCEP-R-2, 86.4% for MERRA and 85.1% for MERRA-2). We think that this may be possibly due to the 4D variational data assimilation method applied. Considering inland stations only, more than 96% exhibit WRMS reduction in the Up direction for all five models, with an average improvement of 3–4% compared with the original ITRF2014 residual time series before ATML correction. Most stations (> 67%) also exhibit horizontal WRMS reductions based on the five models, but of small magnitudes, with most improvements (> 76%) less than 5%. In particular, most stations in South America, South Africa, Oceania and the Southern Oceans show larger WRMS reductions with MERRA-2, while all other four SP datasets lead to larger WRMS reduction for the Up component than MERRA-2 in Europe. Through comparison of the daily pressure variation from the five SP models, we conclude that the bigger model differences in the SP-induced surface displacements and their impacts on the ITRF2014 residuals for coastal/island stations are mainly due to the IB correction based on the different land–sea masks. A unique high spatial resolution land–sea mask should be applied in the future, so that model differences would come from only SP grids. Further research is also required to compare the ATML effect in ice-covered and high mountainous regions, for example the Qinghai–Tibet Plateau in China, the Andes in South America, etc., where larger pressure differences between models tend to occur. Numéro de notice : A2020-159 Affiliation des auteurs : Géodésie+Ext (mi2018-2019) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01370-y Date de publication en ligne : 20/03/2020 En ligne : https://doi.org/10.1007/s00190-020-01370-y Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94813
in Journal of geodesy > vol 94 n°4 (April 2020) . - n° 42[article]ITRF2014, Earth figure changes, and geocenter velocity: Implications for GIA and recent ice melting / Laurent Métivier in Journal of geophysical research : Solid Earth, vol 125 n° 2 (February 2020)
[article]
Titre : ITRF2014, Earth figure changes, and geocenter velocity: Implications for GIA and recent ice melting Type de document : Article/Communication Auteurs : Laurent Métivier , Auteur ; Hélène Rouby , Auteur ; Paul Rebischung , Auteur ; Zuheir Altamimi , Auteur Année de publication : 2020 Projets : 2-Pas d'info accessible - article non ouvert / Article en page(s) : n° e2019JB018333 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] figure de la Terre
[Termes IGN] fonte des glaces
[Termes IGN] harmonique sphérique
[Termes IGN] International Terrestrial Reference Frame
[Termes IGN] manteau terrestre
[Termes IGN] mouvement du géocentre
[Termes IGN] rebond post-glaciaire
[Termes IGN] vitesse de déplacementRésumé : (auteur) Using a selection of Global Navigation Satellite System vertical velocities from the latest solution of the International Terrestrial Reference Frame (ITRF) ITRF2014, we calculate the degree-1 and degree-2 spherical harmonics coefficients (SHC) of the solid Earth figure changes at different dates, with realistic errors that take into account the inhomogeneity of the network. We find that the SHC are globally close to zero except the zonal coefficients, which show values notably larger than those derived from different glacial isostatic adjustment (GIA) models and which have tended to increase during the time span of observations. We show that these differences are most probably due to global recent ice melting (RIM). Assuming elastic RIM deformation, we then investigate the Earth's geocenter velocity and the geoid oblateness time evolution (J2-rate) derived from our SHC estimations. The obtained geocenter velocity reaches 0.9 ± 0.5 mm/year in 2013 with a z-component of 0.8 ± 0.4 mm/year, which is slightly larger than previous estimations. We compare our J2-rate estimations with observations. Our estimations show a similar acceleration in J2 after 2000. However, our estimates are notably larger than the observations. This indicates either that the J2-rate due to GIA processes is lower than expected (as proposed by Nakada et al., 2015, 2016) or that the deformation induced by RIM is not purely elastic, or both. Finally, we show that viscous relaxation or phase transitions in the mantle transition zone may only partly explain this discrepancy. This raises the question of the accuracy of current mass estimations of RIM and GIA models. Numéro de notice : A2020-363 Affiliation des auteurs : UMR IPGP-Géod (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2019JB018333 Date de publication en ligne : 02/01/2020 En ligne : https://doi.org/10.1029/2019JB018333 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98263
in Journal of geophysical research : Solid Earth > vol 125 n° 2 (February 2020) . - n° e2019JB018333[article]
Titre : Description and evaluation of DTRF2014, JTRF2014 and ITRF2014 Type de document : Rapport Auteurs : Zuheir Altamimi , Éditeur scientifique ; Wolfgang R. Dick, Éditeur scientifique Editeur : Francfort sur le Main : Bundesamt für Kartographie und Geodäsie Année de publication : 2020 Collection : IERS Technical note, ISSN 1019-4568 num. 40 Importance : 170 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-86482-137-0 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] International Terrestrial Reference FrameNote de contenu : Foreword / Zuheir Altamimi
1-- DTRF2014: DGFI-TUM realization of the International Terrestrial Reference System (ITRS) / Mathis Bloßfeld, Manuela Seitz, Detlef Angermann, and Florian Seitz
2-- JTRF2014: Analysis, Results and Comparisons to ITRF2014 and DTRF2014 / Claudio Abbondanza, Toshio Michael Chin, Richard S. Gross, Michael B. Heflin, Jay W. Parker, Benedikt S. Soja, Tonie M. van Dam, and Xiaoping WuI
3-- TRS Center evaluation of DTRF2014 and JTRF2014 with respect to ITRF2014 / Zuheir Altamimi, Paul Rebischung, Xavier Collilieux, and Laurent Métivier
4-- Comparison of latest ITRS realizations: ITRF2014, JTRF2014 and DTRF2014 / Detlef Angermann, Mathis Bloßfeld, Manuela Seitz, and Sergei Rudenko
5-- A comparison of the DTRF2014, ITRF2014, and JTRF2014 solutions using DORIS / Guilhem Moreaux, Hugues Capdeville, Claudio Abbondanza, Mathis Bloßfeld, Jean-Michel Lemoine, and Pascale Ferrage
6-- Assessment of DTRF2014 and ITRF2014 by Satellite Laser Ranging / José Rodríguez
7-- ITRS realizations and their impact on VLBI combined EOP and Scale / Sabine Bachmann and Daniela ThallerNuméro de notice : 17623 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Recueil / ouvrage collectif nature-HAL : RappRech DOI : sans Date de publication en ligne : 20/03/2020 En ligne : http://www.iers.org/TN40 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97123 Description and evaluation of DTRF2014, JTRF2014 and ITRF2014, ch. 3. ITRS Center evaluation of DTRF2014 and JTRF2014 with respect to ITRF2014 / Zuheir Altamimi (2020)
Titre de série : Description and evaluation of DTRF2014, JTRF2014 and ITRF2014, ch. 3 Titre : ITRS Center evaluation of DTRF2014 and JTRF2014 with respect to ITRF2014 Type de document : Chapitre/Contribution Auteurs : Zuheir Altamimi , Auteur ; Paul Rebischung , Auteur ; Xavier Collilieux , Auteur ; Laurent Métivier , Auteur Editeur : Francfort sur le Main : Bundesamt für Kartographie und Geodäsie Année de publication : 2020 Collection : IERS Technical note, ISSN 1019-4568 num. 40 Projets : 1-Pas de projet / Importance : pp 71 - 78 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] International Terrestrial Reference FrameRésumé : (auteur) The three reference frame solutions used the same input data submit-ted by the IERS Technique Centers (IDS, IGS, ILRS and IVS) for the ITRF2014 computation, provided in the form of time series of station positions and Earth Orientation Parameters (EOPs). The reader may refer to the following publications for more details regarding the technique solutions: IDS: Moreaux et al., 2016, IGS: Rebischung et al.,2016, ILRS: Luceri and Pavlis, 2016, IVS: Bachmann et al., 2015 and Nothnagel et al., 2015. Numéro de notice : H2020-005 Affiliation des auteurs : UMR IPGP-Géod (2020- ) Thématique : POSITIONNEMENT Nature : Chapître / contribution nature-HAL : ChRappRech DOI : sans Date de publication en ligne : 20/03/2020 En ligne : https://www.iers.org/SharedDocs/Publikationen/EN/IERS/Publications/tn/TechnNote4 [...] Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97124 PermalinkIERS annual report 2018, 3.6.2. ITRS Combination Centres: Institut National de l’Information Geógraphique et Forestière (IGN) / Zuheir Altamimi (2020)PermalinkPosition, navigation, and timing technologies in the 21st century: Integrated satellite navigation, sensor systems, and civil applications, ch. 27. Global geodesy and reference frames / Chris Rizos (2020)PermalinkSemi-kinematic geodetic reference frame based on the ITRF2014 for Malaysia / M. Azhari in Journal of geodetic science, vol 10 n° 1 (January 2020)PermalinkThe International Terrestrial Reference Frame: lessons from ITRF2014 / Zuheir Altamimi in Rendiconti Lincei. Scienze Fisiche e Naturali, vol 29 suppl 1 (June 2018)PermalinkAssessment of the possible contribution of space ties on-board GNSS satellites to the terrestrial reference frame / Sara Bruni in Journal of geodesy, vol 92 n° 4 (April 2018)PermalinkApport de la prise en compte de la dépendance spatiotemporelle des séries temporelles de positions GNSS à l’estimation d’un système de référence / Clément Benoist (2018)PermalinkBruit de scintillation dans les séries temporelles de positions GNSS : origines et conséquences / Paul Rebischung (2018)PermalinkComparing non-linear geocenter motion derived from GNSS and SLR observations corrected for loading and thermoelastic deformation / Kristel Chanard (2018)PermalinkComparison of the seasonal displacement parameters estimated in the ITRF2014 processing, what can we learn? / Xavier Collilieux (2018)Permalink
HDR in 2006
IAG Vice-President