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ITRF2020: an augmented reference frame refining the modeling of nonlinear station motions / Zuheir Altamimi in Journal of geodesy, vol 97 n° 5 (May 2023)  

Public [article]  inJournal of geodesy > vol 97 n° 5 (May 2023) . - n° 47 Titre : ITRF2020: an augmented reference frame refining the modeling of nonlinear station motions Type de document : Article/Communication Auteurs : Zuheir Altamimi , Auteur ; Paul Rebischung , Auteur ; Xavier Collilieux , Auteur ; Laurent Métivier , Auteur ; Kristel Chanard , Auteur Année de publication : 2023 Article en page(s) : n° 47 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] International Terrestrial Reference Frame Résumé : (auteur) To better describe the shape of the constantly deforming Earth’s surface, the ITRF2020 is provided as an augmented terrestrial reference frame that precisely models nonlinear station motions for both seasonal (annual and semi-annual) signals present in the station position time series and Post-Seismic Deformation (PSD) for sites impacted by major earthquakes. Reprocessed solutions in the form of station position time series and Earth Orientation Parameters using the full observation history provided by the four space geodetic techniques (DORIS, GNSS, SLR and VLBI) were used as input data, spanning 28, 27, 38 and 41 years of observations, respectively. The ITRF2020 long-term origin follows linearly with time the Earth’s Center of Mass (CM) as sensed by SLR, based on observations collected over the time span 1993.0–2021.0. We evaluate the accuracy of the ITRF2020 long-term origin position and time evolution by comparison to previous solutions, namely ITRF2014, ITRF2008 and ITRF2005, to be at the level of or better than 5 mm and 0.5 mm/yr, respectively. The ITRF2020 long-term scale is defined by a rigorous weighted average of selected VLBI sessions up to 2013.75 and SLR weekly solutions covering the 1997.75–2021.0 time span. For the first time of the ITRF history, the scale agreement between SLR and VLBI long-term solutions is at the level of 0.15 ppb (1 mm at the equator) at epoch 2015.0, with no drift. To accommodate most of ITRF2020 users, the seasonal station coordinate variations are provided in the CM as well as in the Center of Figure frames, together with a seasonal geocenter motion model. While the PSD parametric models were determined by fitting GNSS data only, they also fit the station position time series of the three other techniques that are colocated with GNSS, demonstrating their high performance in describing site post-seismic trajectories. Numéro de notice : A2023-098 Affiliation des auteurs : UMR IPGP-Géod (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-023-01738-w Date de publication en ligne : 19/05/2023 En ligne : https://doi.org/10.1007/s00190-023-01738-w Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103231 [article]

GRGS numerical simulations for a GRASP-like mission: A way to reach the GGOS goal for terrestrial reference frame / Arnaud Pollet in Journal of geodesy, vol 97 n° 5 (May 2023)  

Public [article]  inJournal of geodesy > vol 97 n° 5 (May 2023) . - n° 45 Titre : GRGS numerical simulations for a GRASP-like mission: A way to reach the GGOS goal for terrestrial reference frame Type de document : Article/Communication Auteurs : Arnaud Pollet , Auteur ; David Coulot , Auteur ; Richard Biancale, Auteur ; Felix Perozans, Auteur ; Sylvain Loyer, Auteur ; J.C. Marty, Auteur ; Susanne Glaser, Auteur ; Vladimir Schott-Guilmault, Auteur ; Jean-Michel Lemoine, Auteur ; Flavien Mercier, Auteur ; Samuel Nahmani , Auteur ; Mioara Mandea, Auteur Année de publication : 2023 Article en page(s) : n° 45 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] International DORIS Service [Termes IGN] mission spatiale [Termes IGN] orbitographie [Termes IGN] positionnement par ITGB [Termes IGN] positionnement par télémétrie laser sur satellite [Termes IGN] repère de référence Résumé : (auteur) In 2009, the geoscience community has fixed an objective of 1 mm accuracy and 0.1 mm/yr stability for the terrestrial reference frame (TRF) realization (Global Geodetic Observing System, GGOS, Meeting the Requirements of a Global Society on a Changing Planet in 2020, Plag and Pearlman in Global geodetic observing system: meeting the requirements of a global society on a changing planet in 2020. Springer, Berlin, 2009. https://doi.org/10.1007/978-3-642-02687-4). This accuracy and stability are needed for diversified studies like climate change, tectonic sciences and more generally any geoscience requiring the use of an accurate and precise TRF. Unfortunately, they are still not reached by the last International Terrestrial Reference Frame. To reach this goal, the use of “multi-technique” satellites as “space-ties” has been studied since 2011 and a few proposals have been made in response to different space agency calls: the Geodetic Reference Antenna in Space (GRASP) mission—NASA Earth Venture 2 call, Eratosthenes-GRASP (E-GRASP)—ESA Earth Explorer 9 (EE9) call, MOBILE—ESA EE10 call, MARVEL—CNES Séminaire de Prospective Scientifique 2019). In this article, we present the numerical simulations carried out by the French Groupe de Recherche de Géodésie Spatiale (GRGS) for the E-GRASP proposal in response to the ESA EE-9 call and their improvements carried out afterwards. These simulations aim to answer three different questions: Is it possible to reach the GGOS requirements for the TRF with the measurements of a GRASP-like satellite like E-GRASP alone? If it is possible, which level of accuracy for the positioning of the on-board antennas is needed? What is the minimal lifetime of a E-GRASP mission to reach the GGOS requirements? The results of these simulations show that a E-GRASP satellite can allow us to reach, after five years, an accuracy close to 1 mm and a stability better than 0.1 mm/yr for the TRF. However, it is necessary to ensure a positioning better than 1 mm for the on-board antennas. We therefore encourage the new ESA GENESIS mission proposal, accepted during the ESA last Ministerial meeting on 23rd November 2022, which takes up the concept of a GRASP-type satellite. Numéro de notice : A2023-227 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-023-01730-4 Date de publication en ligne : 15/05/2023 En ligne : https://doi.org/10.1007/s00190-023-01730-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103247 [article]