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Monitoring of extreme land hydrology events in central Poland using GRACE, land surface models and absolute gravity data / Joanna Kuczynska-Siehien in Journal of applied geodesy, vol 13 n° 3 (July 2019)  

Public [article]  inJournal of applied geodesy > vol 13 n° 3 (July 2019) . - pp 229 – 243 Titre : Monitoring of extreme land hydrology events in central Poland using GRACE, land surface models and absolute gravity data Type de document : Article/Communication Auteurs : Joanna Kuczynska-Siehien, Auteur ; Dimitrios Piretzidis, Auteur ; Michael G. Sideris, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 229 – 243 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] analyse diachronique [Termes descripteurs IGN] analyse spectrale [Termes descripteurs IGN] données GLDAS [Termes descripteurs IGN] données GRACE [Termes descripteurs IGN] gravimètre absolu [Termes descripteurs IGN] inondation [Termes descripteurs IGN] levé gravimétrique [Termes descripteurs IGN] modèle numérique de surface [Termes descripteurs IGN] Pologne [Termes descripteurs IGN] risque naturel [Termes descripteurs IGN] sécheresse [Termes descripteurs IGN] surveillance hydrologique [Termes descripteurs IGN] variation temporelle Résumé : (auteur) This study deals with the analysis of temporal gravity variations in central Poland, deduced from multiple sources and covering the period from 2002–2016. The gravity data sets used comprise GRACE monthly solutions, GLDAS land surface models and absolute gravimeter measurements from the FG-5 gravimeter located in Józefosław, Poland. All data are corrected using standard processing methods in order to include the same gravity effects. After removing the annual and semi-annual components from all data using least-squares spectral analysis and seasonal-trend decomposition, the deseasoned time series are derived and examined for signatures of extreme hydrological events. The signatures of several severe drought and flood conditions affecting Poland and central Europe are identified. A complementary correlation analysis is performed to assess the level of agreement between different data sources. A higher correlation is shown when the analysis is restricted in the 2009–2012 period that includes the 2010 extreme flood and 2011 increased precipitation events, both affecting Poland. Numéro de notice : A2019-286 Thématique : IMAGERIE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2019-0003 date de publication en ligne : 20/04/2019 En ligne : https://doi.org/10.1515/jag-2019-0003 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93121 [article]

On the assimilation of absolute geodetic dynamic topography in a global ocean model: impact on the deep ocean state / Alexey Androsov in Journal of geodesy, vol 93 n° 2 (February 2019)  

Public [article]  inJournal of geodesy > vol 93 n° 2 (February 2019) . - pp 141 - 157 Titre : On the assimilation of absolute geodetic dynamic topography in a global ocean model: impact on the deep ocean state Type de document : Article/Communication Auteurs : Alexey Androsov, Auteur ; Lars Nerger, Auteur ; Reiner Schnur, Auteur ; Alberta Albertella, Auteur ; Reiner Rummel, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 141 - 157 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] assimilation des données [Termes descripteurs IGN] circulation océanique [Termes descripteurs IGN] données altimétriques [Termes descripteurs IGN] données CHAMP [Termes descripteurs IGN] données GOCE [Termes descripteurs IGN] données GRACE [Termes descripteurs IGN] filtre de Kalman [Termes descripteurs IGN] geoïde marin [Termes descripteurs IGN] géoïde terrestre [Termes descripteurs IGN] hauteurs de mer [Termes descripteurs IGN] modèle de simulation [Termes descripteurs IGN] modèle océanographique [Termes descripteurs IGN] océanographie dynamique [Termes descripteurs IGN] salinité [Termes descripteurs IGN] température de surface de la mer Résumé : (auteur) General ocean circulation models are not perfect. Forced with observed atmospheric fluxes they gradually drift away from measured distributions of temperature and salinity. We suggest data assimilation of absolute dynamical ocean topography (DOT) observed from space geodetic missions as an option to reduce these differences. Sea surface information of DOT is transferred into the deep ocean by defining the analysed ocean state as a weighted average of an ensemble of fully consistent model solutions using an error-subspace ensemble Kalman filter technique. Success of the technique is demonstrated by assimilation into a global configuration of the ocean circulation model FESOM over 1 year. The dynamic ocean topography data are obtained from a combination of multi-satellite altimetry and geoid measurements. The assimilation result is assessed using independent temperature and salinity analysis derived from profiling buoys of the AGRO float data set. The largest impact of the assimilation occurs at the first few analysis steps where both the model ocean topography and the steric height (i.e. temperature and salinity) are improved. The continued data assimilation over 1 year further improves the model state gradually. Deep ocean fields quickly adjust in a sustained manner: A model forecast initialized from the model state estimated by the data assimilation after only 1 month shows that improvements induced by the data assimilation remain in the model state for a long time. Even after 11 months, the modelled ocean topography and temperature fields show smaller errors than the model forecast without any data assimilation. Numéro de notice : A2019-076 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1151-1 date de publication en ligne : 12/05/2018 En ligne : https://doi.org/10.1007/s00190-018-1151-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92190 [article]

A Terrestrial Reference Frame realised on the observation level using a GPS-LEO satellite constellation / Daniel Koenig in Journal of geodesy, vol 92 n° 11 (November 2018)  

Public [article]  inJournal of geodesy > vol 92 n° 11 (November 2018) . - pp 1299 - 1312 Titre : A Terrestrial Reference Frame realised on the observation level using a GPS-LEO satellite constellation Type de document : Article/Communication Auteurs : Daniel Koenig, Auteur Année de publication : 2018 Article en page(s) : pp 1299 - 1312 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes descripteurs IGN] champ de pesanteur terrestre [Termes descripteurs IGN] données GPS [Termes descripteurs IGN] données GRACE [Termes descripteurs IGN] géocentre [Termes descripteurs IGN] International Terrestrial Reference Frame [Termes descripteurs IGN] transformation de Helmert Résumé : (Auteur) Applying a one-step integrated process, i.e. by simultaneously processing all data and determining all satellite orbits involved, a Terrestrial Reference Frame (TRF) consisting of a geometric as well as a dynamic part has been determined at the observation level using the EPOS-OC software of Deutsches GeoForschungsZentrum. The satellite systems involved comprise the Global Positioning System (GPS) as well as the twin GRACE spacecrafts. Applying a novel approach, the inherent datum defect has been overcome empirically. In order not to rely on theoretical assumptions this is done by carrying out the TRF estimation based on simulated observations and using the associated satellite orbits as background truth. The datum defect is identified here as the total of all three translations as well as the rotation about the z-axis of the ground station network leading to a rank-deficient estimation problem. To rectify this singularity, datum constraints comprising no-net translation (NNT) conditions in x, y, and z as well as a no-net rotation (NNR) condition about the z-axis are imposed. Thus minimally constrained, the TRF solution covers a time span of roughly a year with daily resolution. For the geometric part the focus is put on Helmert transformations between the a priori and the estimated sets of ground station positions, and the dynamic part is represented by gravity field coefficients of degree one and two. The results of a reference solution reveal the TRF parameters to be estimated reliably with high precision. Moreover, carrying out a comparable two-step approach using the same data and models leads to parameters and observational residuals of worse quality. A validation w.r.t. external sources shows the dynamic origin to coincide at a level of 5 mm or better in x and y, and mostly better than 15 mm in z. Comparing the derived GPS orbits to IGS final orbits as well as analysing the SLR residuals for the GRACE satellites reveals an orbit quality on the few cm level. Additional TRF test solutions demonstrate that K-Band Range-Rate observations between both GRACE spacecrafts are crucial for accurately estimating the dynamic frame’s orientation, and reveal the importance of the NNT- and NNR-conditions imposed for estimating the components of the dynamic geocenter. Numéro de notice : A2018-464 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1121-7 date de publication en ligne : 27/02/2018 En ligne : https://doi.org/10.1007/s00190-018-1121-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91063 [article]

Migrating pattern of deformation prior to the Tohoku-Oki earthquake revealed by GRACE data / Isabelle Panet in Nature geoscience, vol 11 n° 5 (May 2018)  

Public [article]  inNature geoscience > vol 11 n° 5 (May 2018) Titre : Migrating pattern of deformation prior to the Tohoku-Oki earthquake revealed by GRACE data Type de document : Article/Communication Auteurs : Isabelle Panet , Auteur ; Sylvain Bonvalot, Auteur ; Clément Narteau, Auteur ; Dominique Remy, Auteur ; Jean-Michel Lemoine, Auteur Année de publication : 2018 Projets : 1-Pas de projet / Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] champ de pesanteur terrestre [Termes descripteurs IGN] déformation de la croute terrestre [Termes descripteurs IGN] données GRACE [Termes descripteurs IGN] Japon [Termes descripteurs IGN] risque naturel [Termes descripteurs IGN] séisme [Termes descripteurs IGN] subduction [Termes descripteurs IGN] tectonique des plaques Résumé : (auteur) Understanding how and when far-field continuous motions lead to giant subduction earthquakes remains a challenge. An important limitation comes from an incomplete description of aseismic mass fluxes at depth along plate boundaries. Here we analyse Earth’s gravity field variations derived from GRACE satellite data in a wide space-time domain surrounding the Mw 9.0 2011 Tohoku-Oki earthquake. We show that this earthquake is the extreme expression of initially silent deformation migrating from depth to the surface across the entire subduction system. Our analysis indeed reveals large-scale gravity and mass changes throughout three tectonic plates and connected slabs, starting a few months before March 2011. Before the Tohoku-Oki earthquake rupture, the gravity variations can be explained by aseismic extension of the Pacific plate slab at mid-upper mantle depth, concomitant with increasing seismicity in the shallower slab. For more than two years after the rupture, the deformation propagated far into the Pacific and Philippine Sea plate interiors, suggesting that subduction accelerated along 2,000 km of the plate boundaries in March 2011. This gravitational image of the earthquake’s long-term dynamics provides unique information on deep and crustal processes over intermediate timescales, which could be used in seismic hazard assessment. Numéro de notice : A2018-118 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1038/s41561-018-0099-3 date de publication en ligne : 09/04/2018 En ligne : https://doi.org/10.1038/s41561-018-0099-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89558 [article]

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)  

Public [article]  inJournal of geophysical research : Solid Earth > vol 123 n° 4 (April 2018) . - pp Titre : Toward a global horizontal and vertical elastic load deformation model derived from GRACE and GNSS station position time series Type de document : Article/Communication Auteurs : Kristel Chanard , Auteur ; Luce Fleitout, Auteur ; Eric Calais, Auteur ; Paul Rebischung , Auteur ; Jean-Philippe Avouac, Auteur Année de publication : 2018 Article en page(s) : pp Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] coordonnées GNSS [Termes descripteurs IGN] déformation horizontale de la croute terrestre [Termes descripteurs IGN] déformation verticale de la croute terrestre [Termes descripteurs IGN] données GRACE [Termes descripteurs IGN] Earth Gravity Model 2008 [Termes descripteurs IGN] erreur systématique [Termes descripteurs IGN] harmonique sphérique [Termes descripteurs IGN] modèle de déformation tectonique [Termes descripteurs IGN] mouvement du géocentre [Termes descripteurs IGN] série temporelle Résumé : (Auteur) We model surface displacements induced by variations in continental water, atmospheric pressure, and non‐tidal oceanic loading, derived from the Gravity and Recovery Climate Experiment (GRACE) for spherical harmonic degrees two and higher. As they are not observable by GRACE, we use at first the degree‐1 spherical harmonic coefficients from (Swenson2008estimating). We compare the predicted displacements with the position time series of 689 globally distributed continuous Global Navigation Satellite System (GNSS) stations. While GNSS vertical displacements are well explained by the model at a global scale, horizontal displacements are systematically underpredicted and out‐of‐phase with GNSS station position time series. We then re‐estimate the degree‐1 deformation field from a comparison between our GRACE‐derived model, with no a priori degree‐1 loads, and the GNSS observations. We show that this approach reconciles GRACE‐derived loading displacements and GNSS station position time series at a global scale, particularly in the horizontal components. Assuming that they reflect surface loading deformation only, our degree‐1 estimates can be translated into geocenter motion time series. We also address and assess the impact of systematic errors in GNSS station position time series at the Global Positioning System (GPS) draconitic period and its harmonics on the comparison between GNSS and GRACE‐derived annual displacements. Our results confirm that surface mass redistributions observed by GRACE, combined with an elastic spherical and layered Earth model, can be used to provide first order corrections for loading deformation observed in both horizontal and vertical components of GNSS station position time series. Numéro de notice : A2018-055 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/2017JB015245 date de publication en ligne : 21/02/2018 En ligne : https://doi.org/10.1002/2017JB015245 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89382 [article]

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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Contribution actuelle de la calotte Antarctique à la variation du niveau marin / Clémence Chupin (2018) 

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Déformation saisonnière de la Terre / Kristel Chanard (2018) 

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Application of the PCA/EOF method for the analysis and modelling of temporal variations of geoid heights over Poland / Walyeldeen Godah in Acta geodaetica et geophysica, vol 52 n° 4 (December 2017)  

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Hydrological excitation of polar motion by different variables from the GLDAS models / Malgorzata Winska in Journal of geodesy, vol 91 n° 12 (December 2017)  

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On the estimation of physical height changes using GRACE satellite mission data – A case study of Central Europe / Walyeldeen Godah in Geodesy and cartography, vol 66 n° 2 (December 2017)  

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Hydrologically-driven crustal stresses and seismicity in the New Madrid Seismic Zone / Timothy J. Craig in Nature communications, vol 8 (2017)  

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Multi-scale modeling of Earth's gravity field in space and time / Shuo Wang in Journal of geodynamics, vol 106 (May 2017)  

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GRACE era variability in the Earth's oblateness: a comparison of estimates from six different sources / Thierry Meyrath in Geophysical journal international, vol 208 n° 2 (February 2017)  

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