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Self-consistent determination of the Earth’s GM, geocenter motion and figure axis orientation / Alexandre Couhert in Journal of geodesy, vol 94 n° 12 (December 2020)  

Public [article]  inJournal of geodesy > vol 94 n° 12 (December 2020) . - n° 113 Titre : Self-consistent determination of the Earth’s GM, geocenter motion and figure axis orientation Type de document : Article/Communication Auteurs : Alexandre Couhert, Auteur ; Christian Bizouard, Auteur ; F. Mercier, Auteur ; Kristel Chanard , Auteur ; Marianne Greff-Lefftz, Auteur ; Pierre Exertier, Auteur Année de publication : 2020 Projets : 1-Pas de projet / Article en page(s) : n° 113 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] données Ajisai [Termes descripteurs IGN] données Jason [Termes descripteurs IGN] données Lageos [Termes descripteurs IGN] données Lares [Termes descripteurs IGN] données Starlette [Termes descripteurs IGN] données Stella [Termes descripteurs IGN] données TLS (télémétrie) [Termes descripteurs IGN] erreur de modèle [Termes descripteurs IGN] harmonique sphérique [Termes descripteurs IGN] incertitude géométrique [Termes descripteurs IGN] mouvement du géocentre [Termes descripteurs IGN] surface de la mer Résumé : (auteur) The very low-degree Earth’s gravity coefficients, associated with the largest-scale mass redistribution in the Earth’s fluid envelope (atmosphere, oceans and continental hydrology), are the most poorly known. In particular, the first three degree geopotential terms are important, as they relate to intrinsic Earth’s mass references: gravitational coefficient (GM) of the Earth (degree 0), geocenter motion (degree 1), Earth’s figure axis orientation (degree 2). This paper presents a self-consistent determination of these three properties of the Earth. The main objective is to deal with the remaining sources of altimetry satellite orbit uncertainties affecting the fundamental record of sea surface height measurements. The analysis identifies the modeling errors, which should be mitigated when estimating the geocenter coordinates from Satellite Laser Ranging (SLR) observations. The long-term behavior of the degree-0 and -2 spherical harmonics is also observed over the 34-year period 1984–2017 from the long-time history of satellite laser tracking to geodetic spherical satellites. From the analysis of the evolution of these two coefficients, constraints regarding the Earth’s rheology and uncertainties in the value of GM could be inferred. Overall, the influence of the orbit characteristics, SLR station ranging/position biases and satellite signature effects, measurement modeling errors (tropospheric corrections, non-tidal deformations) are also discussed. Numéro de notice : A2020-330 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01450-z date de publication en ligne : 18/11/2020 En ligne : https://doi.org/10.1007/s00190-020-01450-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96858 [article]

Accounting for spatiotemporal correlations of GNSS coordinate time series to estimate station velocities / Clément Benoist in Journal of geodynamics, vol 135 (April 2020)  

Public [article]  inJournal of geodynamics > vol 135 (April 2020) . - n° 101693 Titre : Accounting for spatiotemporal correlations of GNSS coordinate time series to estimate station velocities Type de document : Article/Communication Auteurs : Clément Benoist , Auteur ; Xavier Collilieux , Auteur ; Paul Rebischung , Auteur ; Zuheir Altamimi , Auteur ; Olivier Jamet , Auteur ; Laurent Métivier , Auteur ; Kristel Chanard , Auteur ; Liliane Bel, Auteur Année de publication : 2020 Projets : GEODESIE / Coulot, David, Université de Paris / Clerici, Christine Article en page(s) : n° 101693 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes descripteurs IGN] corrélation [Termes descripteurs IGN] covariance [Termes descripteurs IGN] données spatiotemporelles [Termes descripteurs IGN] repère de référence terrestre conventionnel [Termes descripteurs IGN] série temporelle [Termes descripteurs IGN] vitesse Résumé : (auteur) It is well known that GNSS permanent station coordinate time series exhibit time-correlated noise. Spatial correlations between coordinate time series of nearby stations are also long-established and generally handled by means of spatial filtering techniques. Accounting for both the temporal and spatial correlations of the noise via a spatiotemporal covariance model is however not yet a common practice. We demonstrate in this paper the interest of using such a spatiotemporal covariance model of the stochastic variations in GNSS time series in order to estimate long-term station coordinates and especially velocities. We provide a methodology to rigorously assess the covariances between horizontal coordinate variations and use it to derive a simple exponential spatiotemporal covariance model for the stochastic variations in the IGS repro2 station coordinate time series. We then use this model to estimate station velocities for two selected datasets of 10 time series in Europe and 11 time series in the USA. We show that coordinate prediction as well as velocity determination from short time series are improved when using this spatiotemporal model, as compared with the case where spatiotemporal correlations are ignored. Numéro de notice : A2020-460 Affiliation des auteurs : Géodésie+Ext (mi2018-2019) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.jog.2020.101693 date de publication en ligne : 13/01/2020 En ligne : https://doi.org/10.1016/j.jog.2020.101693 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95385 [article]

A warning against over-interpretation of seasonal signals measured by the Global Navigation Satellite System / Kristel Chanard in Nature communications, vol 11 (2020)  

Public [article]  inNature communications > vol 11 (2020) . - n° 1375 Titre : A warning against over-interpretation of seasonal signals measured by the Global Navigation Satellite System Type de document : Article/Communication Auteurs : Kristel Chanard , Auteur ; Marianne Metois, Auteur ; Paul Rebischung , Auteur ; Jean-Philippe Avouac, Auteur Année de publication : 2020 Projets : TOSCA / Article en page(s) : n° 1375 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes descripteurs IGN] erreur systématique [Termes descripteurs IGN] variation saisonnière Résumé : (auteur [introduction] In a recent study, Panda et al. claim that seasonal strain across the Himalaya indicates seasonal slow slip on the Main Himalayan Thrust (MHT) fault driven by hydrological loading related to the monsoon and driving seasonal variations of seismicity. While we find the analysis interesting, we spell out some reasons why the claim should be considered with caution. [...] Numéro de notice : A2020-365 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1038/s41467-020-15100-7 date de publication en ligne : 13/03/2020 En ligne : https://doi.org/10.1038/s41467-020-15100-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96831 [article]

Data-adaptive spatio-temporal filtering of GRACE data / Paoline Prevost in Geophysical journal international, vol 219 n° 3 (December 2019)  

Public [article]  inGeophysical journal international > vol 219 n° 3 (December 2019) . - pp 2034 - 2055 Titre : Data-adaptive spatio-temporal filtering of GRACE data Type de document : Article/Communication Auteurs : Paoline Prevost, Auteur ; Kristel Chanard , Auteur ; Luce Fleitout, Auteur ; Eric Calais, Auteur ; Damian Walwer, Auteur ; Tonie M. van Dam, Auteur ; Michael Ghil, Auteur Année de publication : 2019 Projets : 2-Pas d'info accessible - article non ouvert / Article en page(s) : pp 2034 - 2055 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes descripteurs IGN] analyse de spectre singulier [Termes descripteurs IGN] données géophysiques [Termes descripteurs IGN] données GRACE [Termes descripteurs IGN] filtrage spatiotemporel [Termes descripteurs IGN] harmonique sphérique Résumé : (auteur) Measurements of the spatio-temporal variations of Earth’s gravity field from the Gravity Recovery and Climate Experiment (GRACE) mission have led to new insights into large spatial mass redistribution at secular, seasonal and subseasonal timescales. GRACE solutions from various processing centres, while adopting different processing strategies, result in rather coherent estimates. However, these solutions also exhibit random as well as systematic errors, with specific spatial patterns in the latter. In order to dampen the noise and enhance the geophysical signals in the GRACE data, we propose an approach based on a data-driven spatio-temporal filter, namely the Multichannel Singular Spectrum Analysis (M-SSA). M-SSA is a data-adaptive, multivariate, and non-parametric method that simultaneously exploits the spatial and temporal correlations of geophysical fields to extract common modes of variability. We perform an M-SSA analysis on 13 yr of GRACE spherical harmonics solutions from five different processing centres in a simultaneous setup. We show that the method allows us to extract common modes of variability between solutions, while removing solution-specific spatio-temporal errors that arise from the processing strategies. In particular, the method efficiently filters out the spurious north–south stripes, which are caused in all likelihood by aliasing, due to the imperfect geophysical correction models and low-frequency noise in measurements. Comparison of the M-SSA GRACE solution with mass concentration (mascons) solutions shows that, while the former remains noisier, it does retrieve geophysical signals masked by the mascons regularization procedure. Numéro de notice : A2019-276 Affiliation des auteurs : Géodésie+Ext (mi2018-2019) Thématique : MATHEMATIQUE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1093/gji/ggz409 date de publication en ligne : 19/09/2019 En ligne : https://doi.org/10.1093/gji/ggz409 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95381 [article]

Sensitivity of acoustic emission triggering to small pore pressure cycling perturbations during brittle creep / Kristel Chanard in Geophysical research letters, vol 46 n° 13 (16 July 2019)  

Public [article]  inGeophysical research letters > vol 46 n° 13 (16 July 2019) . - pp 7414 - 7423 Titre : Sensitivity of acoustic emission triggering to small pore pressure cycling perturbations during brittle creep Type de document : Article/Communication Auteurs : Kristel Chanard , Auteur ; Aurélien Nicolas, Auteur ; T. Hatano, Auteur ; F. Petrelis, Auteur ; Soumaya Latour, Auteur ; Sergio Vinciguerra, Auteur ; Alexandre Schubnel, Auteur Année de publication : 2019 Projets : 3-projet - voir note / Article en page(s) : pp 7414 - 7423 Note générale : bibliographie This work was funded by the Laboratoire de Recherche Commun “Yves Rocard” (ENS-CEA-CNRS) and the ERC Realism (2016-grant 681346). Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] analyse de sensibilité [Termes descripteurs IGN] Fontainebleau, forêt de [Termes descripteurs IGN] grès [Termes descripteurs IGN] onde acoustique [Termes descripteurs IGN] séisme Résumé : (auteur) Fluid‐induced stress perturbations in the crust at seismogenic depths caused by sources such as tidal or seasonal loading may trigger earthquakes. We investigate the role of small periodic pore pressure (Pp) perturbation in rupture nucleation by performing laboratory triaxial creep experiments on Fontainebleau sandstone, saturated in water, under sinusoidal Pp variations. Results show that recorded acoustic emissions (AEs) correlate with Pp as the rock approaches failure. More interestingly, AEs occur significantly more when Pp is decreasing, that is, when strain rate is maximum with a progressive increase of Pp‐AEs correlation in time as the rock approaches failure. This suggests that the correlation of small stress perturbations and AEs not only depends on Pp amplitude but also on the criticality of the rock. Observations at the laboratory scale support field observations where tidal loading may have modulated seismic rates during the nucleation phase of the 2004 Sumatra‐Andaman and 2011 Tohoku‐Oki earthquakes. Numéro de notice : A2019-406 Affiliation des auteurs : Géodésie+Ext (mi2018-2019) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1029/2019GL082093 date de publication en ligne : 01/07/2019 En ligne : https://doi.org/10.1029/2019GL082093 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93516 [article]

IX Hotine-Marussi Symposium on Mathematical Geodesy. Review of reference frame representations for a deformable Earth / Zuheir Altamimi (2019)  

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Identification and extraction of seasonal geodetic signals due to surface load variations / Stacy Larochelle in Journal of geophysical research : Solid Earth, vol 123 n° 12 (December 2018)  

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Toward a global horizontal and vertical elastic load deformation model derived from GRACE and GNSS station position time series / Kristel Chanard in Journal of geophysical research : Solid Earth, vol 123 n° 4 (April 2018)  

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Constraints on transient viscoelastic rheology of the asthenosphere from seasonal deformation / Kristel Chanard in Geophysical research letters, vol 45 n° 5 (15 March 2018)  

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Bruit de scintillation dans les séries temporelles de positions GNSS / Paul Rebischung (2018) 

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Comparing non-linear geocenter motion derived from GNSS and SLR observations corrected for loading and thermoelastic deformation / Kristel Chanard (2018)

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Comparison of the seasonal displacement parameters estimated in the ITRF2014 processing, what can we learn? / Xavier Collilieux (2018)

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Déformation saisonnière de la Terre / Kristel Chanard (2018) 

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ITRF and seasonal station motions / Zuheir Altamimi (2018)

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ITRF: Three decades of research and development, current status and future plans / Zuheir Altamimi (2018)

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