Descripteur
Documents disponibles dans cette catégorie (59)
Ajouter le résultat dans votre panier
Visionner les documents numériques
Affiner la recherche Interroger des sources externes
Etendre la recherche sur niveau(x) vers le bas
Evidence for postglacial signatures in gravity gradients: A clue in lower mantle viscosity / Laurent Métivier in Earth and planetary science letters, vol 452 (October 2016)
[article]
Titre : Evidence for postglacial signatures in gravity gradients: A clue in lower mantle viscosity Type de document : Article/Communication Auteurs : Laurent Métivier , Auteur ; Lambert Caron, Auteur ; Marianne Greff-Lefftz, Auteur ; Gwendoline Pajot-Métivier , Auteur ; Luce Fleitout, Auteur ; Hélène Rouby , Auteur Année de publication : 2016 Article en page(s) : pp 146 - 156 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] Amérique du nord
[Termes IGN] anomalie de pesanteur
[Termes IGN] déformation de la croute terrestre
[Termes IGN] gradient de gravitation
[Termes IGN] manteau terrestre
[Termes IGN] paléocontinent
[Termes IGN] viscositéRésumé : (auteur) The Earth's surface was depressed under the weight of ice during the last glaciations. Glacial Isostatic Adjustment (GIA) induces the slow recession of the trough that is left after deglaciation and is responsible for a contemporary uplift rate of more than 1 cm/yr around Hudson Bay. The present-day residual depression, an indicator of still-ongoing GIA, is difficult to identify in the observed topography, which is predominantly sensitive to crustal heterogeneities. According to the most widespread GIA models, which feature a viscosity of 2–3×1021 Pa s2–3×1021 Pa s on top of the lower mantle, the trough is approximately 100 m deep and cannot explain the observed gravity anomalies across North America. These large anomalies are therefore usually attributed to subcontinental density heterogeneities in the tectosphere or to slab downwelling in the deep mantle.
Here, we use observed gravity gradients (GG) to show that the uncompensated GIA trough is four times larger than expected and that it is the main source of the North American static gravity signal. We search for the contribution to these GGs from mantle mass anomalies, which are deduced from seismic tomography and are mechanically coupled to the global mantle flow. This contribution is found to be small over Laurentia, and at least 82% of the GGs are caused by GIA. Such a contribution from GIA in these GG observations implies a viscosity that is greater than 1022 Pa s1022 Pa s in the lower mantle.
Our conclusions are a plea for GIA models with a highly viscous lower mantle, which confirm inferences from mantle dynamic models. Any change in GIA modelling has important paleoclimatological and environmental implications, encouraging scientists to re-evaluate the past ice history at a global scale. These implications, in turn, affect the contribution of bedrock uplift to the contemporaneous mass balance over Antarctica and Greenland and thus the present-day ice-melting rate as deduced from the GRACE space mission. Additionally, studies of the thermo-chemical structure of the lithosphere/crust under North America that exploit gravity or geodetic data should be corrected for a GIA model, which is not the case today.Numéro de notice : A2016-906 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.epsl.2016.07.034 Date de publication en ligne : 16/08/2016 En ligne : http://dx.doi.org/10.1016/j.epsl.2016.07.034 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83034
in Earth and planetary science letters > vol 452 (October 2016) . - pp 146 - 156[article]MIDAS robust trend estimator for accurate GPS station velocities without step detection / Geoffrey Blewitt in Journal of geophysical research : Solid Earth, vol 121 n° 3 (March 2016)
[article]
Titre : MIDAS robust trend estimator for accurate GPS station velocities without step detection Type de document : Article/Communication Auteurs : Geoffrey Blewitt, Auteur ; Corné Kremer, Auteur ; William C. Hammond, Auteur ; Julien Gazeaux , Auteur Année de publication : 2016 Article en page(s) : pp 2054 - 2068 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] Amérique du nord
[Termes IGN] coordonnées GPS
[Termes IGN] estimateur
[Termes IGN] méthode robuste
[Termes IGN] série temporelle
[Termes IGN] station GPS
[Termes IGN] valeur aberrante
[Termes IGN] vitesseRésumé : (auteur) Automatic estimation of velocities from GPS coordinate time series is becoming required to cope with the exponentially increasing flood of available data, but problems detectable to the human eye are often overlooked. This motivates us to find an automatic and accurate estimator of trend that is resistant to common problems such as step discontinuities, outliers, seasonality, skewness, and heteroscedasticity. Developed here, Median Interannual Difference Adjusted for Skewness (MIDAS) is a variant of the Theil‐Sen median trend estimator, for which the ordinary version is the median of slopes vij = (xj–xi)/(tj–ti) computed between all data pairs i > j. For normally distributed data, Theil‐Sen and least squares trend estimates are statistically identical, but unlike least squares, Theil‐Sen is resistant to undetected data problems. To mitigate both seasonality and step discontinuities, MIDAS selects data pairs separated by 1 year. This condition is relaxed for time series with gaps so that all data are used. Slopes from data pairs spanning a step function produce one‐sided outliers that can bias the median. To reduce bias, MIDAS removes outliers and recomputes the median. MIDAS also computes a robust and realistic estimate of trend uncertainty. Statistical tests using GPS data in the rigid North American plate interior show ±0.23 mm/yr root‐mean‐square (RMS) accuracy in horizontal velocity. In blind tests using synthetic data, MIDAS velocities have an RMS accuracy of ±0.33 mm/yr horizontal, ±1.1 mm/yr up, with a 5th percentile range smaller than all 20 automatic estimators tested. Considering its general nature, MIDAS has the potential for broader application in the geosciences. Numéro de notice : A2016--176 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/2015JB012552 Date de publication en ligne : 12/02/2016 En ligne : https://doi.org/10.1002/2015JB012552 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91799
in Journal of geophysical research : Solid Earth > vol 121 n° 3 (March 2016) . - pp 2054 - 2068[article]Documents numériques
en open access
MIDAS robust trend estimator ... - pdf éditeurAdobe Acrobat PDF Marine terraces and rates of vertical tectonic motion: The importance of glacio-isostatic adjustment along the Pacific coast of central North America / Alexander R. Simms in GSA bulletin, vol 128 n° 1-2 ([01/01/2016])
[article]
Titre : Marine terraces and rates of vertical tectonic motion: The importance of glacio-isostatic adjustment along the Pacific coast of central North America Type de document : Article/Communication Auteurs : Alexander R. Simms, Auteur ; Hélène Rouby , Auteur ; Kurt Lambeck, Auteur Année de publication : 2016 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Amérique du nord
[Termes IGN] déformation verticale de la croute terrestre
[Termes IGN] fond marin
[Termes IGN] littoral
[Termes IGN] niveau de la mer
[Termes IGN] Pacifique nord
[Termes IGN] rebond post-glaciaire
[Termes IGN] tectonique des plaquesRésumé : (auteur) Differences in marine terrace elevations across the Pacific coast of North America have long been assumed to be a result of differences in the rates of tectonic motion. However, other processes, particularly glacio-isostatic adjustment, lead to regional variations in sea levels. In this study, we compiled the elevations of marine isotope stage (MIS) 5e (ca. 119–129 ka), 5c (ca. 106 ka), and 5a (ca. 84 ka) terraces across the Pacific coast of central North America and compared these regional variations in elevation with model predictions of glacio-isostatic adjustment after correcting for tectonics. These predictions are generally consistent with the observed trends in the elevations of the terraces and show that this process created up to 20 m of coeval variation in local sea levels along the Pacific coast of central North America (between 20°N and 45°N) during MIS 5c and MIS 5a, but less, ∼4 m, during MIS 5e. Accounting for glacio-isostatic adjustment reduces the variability in uplift rates calculated at individual locations using different-aged terraces as datums. Ignoring glacio-isostatic adjustment leads to overestimated uplift rates by an average of 40%, but up to 72%, across the Pacific coast of central North America. An understanding of regional variations in glacio-isostatic adjustment–corrected sea levels also contributes to the correct identification of marine terraces with mistaken ages. Numéro de notice : A2016--188 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1130/B31299.1 Date de publication en ligne : 29/06/2015 En ligne : https://doi.org/10.1130/B31299.1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91830
in GSA bulletin > vol 128 n° 1-2 [01/01/2016][article]Quality evaluation of the weekly vertical loading effects induced from continental water storage models / Z. Li (2016)
Titre : Quality evaluation of the weekly vertical loading effects induced from continental water storage models Type de document : Article/Communication Auteurs : Z. Li, Auteur ; Tonie M. van Dam, Auteur ; Xavier Collilieux , Auteur ; Zuheir Altamimi , Auteur ; Paul Rebischung , Auteur ; Samuel Nahmani , Auteur Editeur : Berlin, Heidelberg, Vienne, New York, ... : Springer Année de publication : 2016 Collection : International Association of Geodesy Symposia, ISSN 0939-9585 num. 143 Conférence : IAG 2013, Scientific assembly, IAG 150 Years Postdam Allemagne Proceedings Springer Importance : pp 45 - 54 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Amérique du nord
[Termes IGN] coordonnées GPS
[Termes IGN] eaux continentales
[Termes IGN] effet de charge
[Termes IGN] hauteur ellipsoïdale
[Termes IGN] série temporelleRésumé : (auteur) To remove continental water storage (CWS) signals from the GPS data, CWS mass models are needed to obtain predicted surface displacements. We compared weekly GPS height time series with five CWS models: (1) the monthly and (2) three-hourly Global Land Data Assimilation System (GLDAS); (3) the monthly and (4) one-hourly Modern-Era Retrospective Analysis for Research and Applications (MERRA); (5) the six-hourly National Centers for Environmental Prediction-Department of Energy (NCEP-DOE) global reanalysis products (NCEP-R-2). We find that of the 344 selected global IGS stations, more than 77% of stations have their weighted root mean square (WRMS) reduced in the weekly GPS height by using both the GLDAS and MERRA CWS products to model the surface displacement, and the best improvement concentrate mainly in North America and Eurasia. We find that the one-hourly MERRA-Land dataset is the most appropriate product for modeling weekly vertical surface displacement caused by CWS variations. The three-hourly GLDAS data ranks the second, while the GLDAS and MERRA monthly products rank the third. The higher spatial resolution MERRA product improves the performance of the CWS model in reducing the scatter of the GPS height by about 2–6% compared with the GLDAS. Under the same spatial resolution, the higher temporal resolution could also improve the performance by almost the same magnitude. We also confirm that removing the ATML and NTOL effects from the weekly GPS height would remarkably improve the performance of CWS model in correcting the GPS height by at least 10%, especially for coastal and island stations. Since the GLDAS product has a much greater latency than the MERRA product, MERRA would be a better choice to model surface displacements from CWS. Finally, we find that the NCEP-R-2 data is not sufficiently precise to be used for this application. Further work is still required to determine the reason. Numéro de notice : C2013-011 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : 10.1007/1345_2015_174 Date de publication en ligne : 30/07/2015 En ligne : https://doi.org/10.1007/1345_2015_174 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91895 Development of a vector-based method for coastal bluffline mapping using LiDAR data and a comparison study in the area of lake Erie / Yunjae Choung in Marine geodesy, vol 36 n° 3 (September - November 2013)
[article]
Titre : Development of a vector-based method for coastal bluffline mapping using LiDAR data and a comparison study in the area of lake Erie Type de document : Article/Communication Auteurs : Yunjae Choung, Auteur ; Rongxing Li, Auteur ; Myung-Hee Jo, Auteur Année de publication : 2013 Article en page(s) : pp 285 - 302 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] Erié, lac
[Termes IGN] extraction du relief
[Termes IGN] falaise
[Termes IGN] Ohio (Etats-Unis)
[Termes IGN] pente
[Termes IGN] rivage
[Termes IGN] triangulation de DelaunayRésumé : (Auteur) This paper introduces a new method for bluffline extraction based on analysis of surface normal vectors derived from a 2.5-dimensional Delaunay triangulation network generated using a set of LiDAR points. The developed method has been implemented and tested for the extraction of blufflines in a section of the Lake Erie coastline near Painesville, Ohio. Comparison of the research results with those generated by a method for bluffline extraction based on slope information along elevation profiles on transects shows an improvement in both horizontal and vertical accuracies in situations where the bluff has a relatively sharp edge formation. Numéro de notice : A2013-712 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/01490419.2013.813878 Date de publication en ligne : 03/11/2015 En ligne : https://doi.org/10.1080/01490419.2013.813878 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32848
in Marine geodesy > vol 36 n° 3 (September - November 2013) . - pp 285 - 302[article]Réservation
Réserver ce documentExemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 230-2013031 RAB Revue Centre de documentation En réserve L003 Disponible L'Amérique du Nord, ressources cartographiques à la BNF / Guillaume Lebailly in Carto, le monde en cartes, n° 16 (mars - avril 2013)PermalinkApplying six classifiers to airborne hyperspectral imagery for detecting giant reed / C. Yang in Geocarto international, vol 27 n° 5 (August 2012)PermalinkEstimating geoid height change in North America: past, present and future / T. Jacob in Journal of geodesy, vol 86 n° 5 (May 2012)PermalinkProperties of boundary-line release criteria in North American tree species / Bryan A. Black in Annals of Forest Science, Vol 66 n° 2 (march 2009)PermalinkSpatially and temporally continuous LAI data sets based on an integrated filtering method: examples from North America / H. Fang in Remote sensing of environment, vol 112 n° 1 (15/01/2008)PermalinkComparison and validation of MODIS and VEGETATION global LAI products over four BigFoot sites in North America / J. Pisek in Remote sensing of environment, vol 109 n° 1 (12 July 2007)PermalinkA data-mining approach to associating MISR smoke plume heights with MODIS fire measurements / D. Mazzoni in Remote sensing of environment, vol 107 n° 1-2 (15 March 2007)PermalinkRaster-network regionalization for watershed data processing / T.L. Whiteaker in International journal of geographical information science IJGIS, vol 21 n° 3-4 (march - april 2007)PermalinkKinematics of the North American–Caribbean-Cocos plates in Central America from new GPS measurements across the Polochic-Motagua fault system / H. Lyon-Caen in Geophysical research letters, vol 33 n° 19 (Octobre 2006)PermalinkUncertainty and confidence in land cover classification using a hybrid classifier approach / W. Liu in Photogrammetric Engineering & Remote Sensing, PERS, vol 70 n° 8 (August 2004)Permalink