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Titre : Clock measurements to improve the geopotential determination Type de document : Article/Communication Auteurs : Guillaume Lion , Auteur ; Isabelle Panet , Auteur ; Pacôme Delva, Auteur ; David Coulot , Auteur ; Peter Wolf, Auteur ; Sébastien Bize, Auteur ; G. Christine, Auteur Editeur : Munich [Allemagne] : European Geosciences Union EGU Année de publication : 2017 Conférence : EGU 2017, General Assembly 23/04/2017 28/04/2017 Vienne Autriche https://www.egu2017.eu/ Note générale : LE POSTER N'EST PAS ENCORE ACCESSIBLE SUR HAL Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] champ de gravitation
[Termes IGN] géoïde altimétrique
[Termes IGN] horloge optique
[Termes IGN] Massif central (France)
[Termes IGN] méthode des moindres carrés
[Termes IGN] précision centimétrique
[Termes IGN] qualité des donnéesRésumé : (Auteur) Comparisons between optical clocks with an accuracy and stability approaching the 10-18 in term of relative frequency shift are opening new perspectives for the direct determination of geopotential at a centimeter-level accuracy in geoid height. However, so far detailed quantitative estimates of the possible improvement in geoid determination when adding such clock measurements to existing data are lacking. In this context, the present work aims at evaluating the contribution of this new kind of direct measurements in determining the geopotential at high spatial resolution (10 km). We consider the Massif Central area, marked by smooth, moderate altitude mountains and volcanic plateaus leading to variations of the gravitational field over a range of spatial scales. In such type of region, the scarcity of gravity data is an important limitation in deriving accurate high resolution geopotential models. We summarize our methodology to assess the contribution of clock data in the geopotential recovery, in combination with ground gravity measurements. We sample synthetic gravity and disturbing potential data from a spherical harmonics geopotential model, and a topography model, up to 10 km resolution; we also build a potential control grid. From the synthetic data, we estimate the disturbing potential by least-squares collocation. Finally, we assess the quality of the reconstructed potential by comparing it to that of the control grid. We show that adding only a few clock data reduces the reconstruction bias significantly and improves the standard deviation by a factor 3. We discuss the role of different parameters, such as the effect of the data coverage and data quality on these results, the trade-off between the measurement noise level and the number of data, and the optimization of the clock data network. Numéro de notice : C2017-062 Affiliation des auteurs : LASTIG+Ext (2016-2019) Thématique : POSITIONNEMENT Nature : Poster nature-HAL : Poster-sans-CL DOI : sans Date de publication en ligne : 15/07/2022 En ligne : https://hal.science/hal-03724673v1 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101283 Documents numériques
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Titre : Monitoring rock glaciers by combining photogrammetric and GNSS-based methods Type de document : Thèse/HDR Auteurs : Fabian Neyer, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2017 Autre Editeur : Zurich : Eidgenossische Technische Hochschule ETH - Ecole Polytechnique Fédérale de Zurich EPFZ Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 99 Importance : 174 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-908440-45-1 Note générale : bibliographie
thesis submitted to attain the degree of doctor of sciences of ETH ZurichLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] Alpes centrales
[Termes IGN] champ de vitesse
[Termes IGN] collocation par moindres carrés
[Termes IGN] déformation de la croute terrestre
[Termes IGN] données localisées 3D
[Termes IGN] glacier
[Termes IGN] image terrestre
[Termes IGN] matrice de covariance
[Termes IGN] pergélisol
[Termes IGN] reconstruction 3D
[Termes IGN] rocher
[Termes IGN] série temporelle
[Termes IGN] SuisseIndex. décimale : 30.60 Géodésie spatiale Résumé : (auteur) Rock glaciers are creeping landforms of perennially frozen ground and belong to the permafrost creeping phenomena. They are mainly composed of rock debris that accumulate in areas of high natural erosion. Ice particles between the rocks cause the moving accumulation in steep terrain to dynamically flow downslope. In the Alpine region, these morphological landforms mainly occur at north-facing mountain slopes in high altitudes above the forest boundary and are known for their sensitivity to climate change.
For several decades, rock glaciers have been monitored for scientific aims, while advances in surveying technologies increased the interest in such studies since the 1990s. Modern technologies in remote sensing (e.g., airborne imagery or satellite-based measurement techniques) are often combined with measurements from field campaigns, i.e., measurements taken directly on a rock glacier (e.g., GNSS, laser-scanning, ground temperature measurements, etc). The high-level goal is to enhance the process understanding, especially with respect to the changing climate: various studies indicate an extended risk of slope failures in steep frozen bedrock due to the global temperature increase. Early recognition of increased activities help to inform local authorities in the endangered areas about the potential hazard before such an event.
The present work is part of the X-Sense project (Nano-Tera.ch), with an interdisciplinary team of scientists that build and operate new low-cost devices for data acquisition, develop new data processing pipelines and algorithms for evaluation, and also gain new insight of natural processes in these regions. Autonomous measurement systems, developed within other work packages in the X-Sense project, observe different permafrost creep areas with high resolution in space and time. Combined with multi-year observations, the derived surface motions are used to obtain an improved process understanding.
This work focuses on the photogrammetric image processing in order to retrieve precise surface displacement estimates. More precisely, image sequences, acquired with two permanently installed commercial digital single-reflex cameras, are used to measure topographic changes in the observed permafrost area. By the combination with high resolution GNSS positioning results, the goal is to obtain precise time series of moving rock boulders at different positions within the field of view. Challenges arising from the combination of different data sets, the development of an automatic processing pipeline, and an improvement of the processing strategy in general, are the main tasks of this thesis.
The study site is the bordering area above the Grabengufer rock glacier (Mattervalley VS, Switzerland), known as the Grabengufer rock slide. Local topographic conditions allowed only a partially good installation geometry for the photogrammetric reconstruction. With respect to a 3D reconstruction without the use of GNSS coordinates, an accuracy increase of about one order of magnitude could be achieved in case these high-precision solutions were integrated. More specifically, respective standard deviations for the East, North, and Height components of 6, 5, and 2 cm were achieved. The stated accuracy, maintained throughout the measurement period of nearly four years (summer months), was obtained in an area of approximately 80m×80 m, with a mean distance of 80 m from the two cameras.
Position time series of moving rock boulders were filtered using the principles of collocation. Analyzing the correlation characteristics of the stochastic signal, an optimal correlation length was computed and used to extract relevant signals from the noise contaminated time series. Velocity was directly estimated as a derived quantity in the collocation process. Furthermore, the techniques of the adaptive collocation approach is presented. This iterative method uses the principles of a dynamically adjusting anisotropic covariance metric. In an example of 2-dimensional velocity fields it is shown that regional compression and extension areas can be extracted.
Results indicate that the observed permafrost area has experienced a mean annual acceleration of about 0.1m/Year between the years 2013 and 2015. During the late summer months of 2015, a prominent temporal acceleration was observed. The mean displacement rate was found to be 0.67m/year, whereas the 3-dimensional displacement is dominated by a translation following the gliding surface. An area in the front of the observed field of view was found to have higher displacement rates, especially during the late summer months, thus it detaches from the otherwise relatively homogeneous flow field.
The methods and principles presented in this work show the potential of monitoring permafrost surface displacements using permanently installed optical cameras in combination with positioning results from permanently mounted GNSS stations. These principles can easily be transfered to other monitoring applications and thus contribute to a better understanding of such processes.Note de contenu : 1 Introduction
2 Study Site
3 Image-Based Displacement Estimation
4 Object Point Reconstruction
5 Collocation for Time Series Analysis
6 Results
7 Conclusions
8 OutlookNuméro de notice : 17458 Affiliation des auteurs : non IGN Autre URL associée : https://doi.org/10.3929/ethz-a-010865360 Thématique : IMAGERIE Nature : Thèse étrangère Note de thèse : thèse : Sciences : ETHZ : 2016 DOI : 10.3929/ethz-a-010865360 En ligne : https://www.sgc.ethz.ch/sgc-volumes/sgk-99.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89683 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 17458-01 33.60 Livre Centre de documentation Photogrammétrie - Lasergrammétrie Disponible Phytosociological analysis of alpine swards and heathlands (pioneer patches) on ridges and peaks in the Julian Alps (NW Slovenia) / Igor Dakskobler in Hacquetia, vol 16 n° 1 (January 2017)
[article]
Titre : Phytosociological analysis of alpine swards and heathlands (pioneer patches) on ridges and peaks in the Julian Alps (NW Slovenia) Type de document : Article/Communication Auteurs : Igor Dakskobler, Auteur ; Bostjan Surina, Auteur Année de publication : 2017 Article en page(s) : pp 49 - 171 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Alpes
[Termes IGN] parc naturel national
[Termes IGN] phytosociologie
[Termes IGN] Slovénie
[Termes IGN] unité phytosociologique
[Vedettes matières IGN] Ecologie forestièreRésumé : (auteur) We conducted a phytosociological analysis of more than 250 relevés in the Julian Alps and compared them with similar communities elsewhere in the Alps and in the Dinaric Alps to describe the following new syntaxa of alpine swards and heathlands from the alliance Caricion firmae (class Elyno-Seslerietea): Saxifrago squarrosae-Caricetum mucronatae, Saussureo pygmaeae-Caricetum rupestris, Seslerio sphaerocephalae-Dryadetum octopetalae, Homogyno discoloris-Vaccinietum gaultherioidis, Saxifrago paniculatae-Caricetum fuliginosae and Homogyno discoloris-Loiseleurietum caricetosum firmae, the new association Achilleo clavennae-Elynetum myosuroidis from the alliance Oxytropido-Elynion and two new syntaxa from the alliance Loiseleurio-Vaccinion (class Loiseleurio-Vaccinietea): Homogyno alpinae-Vaccinietum gaultherioidis and Empetro-Vaccinietum gaultherioidis rhododendretosum hirsuti. Many species that are rare, of conservation concern or protected in Slovenia occur in the newly described communities. Numéro de notice : A2017-003 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1515/hacq-2016-0022 En ligne : https://doi.org/10.1515/hacq-2016-0022 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83414
in Hacquetia > vol 16 n° 1 (January 2017) . - pp 49 - 171[article]Les prairies de l’estuaire de la Loire : étude de la dynamique de la végétation de 1982 à 2014 / Mathieu Le Dez in Mappemonde, n° 119 (janvier 2017)
[article]
Titre : Les prairies de l’estuaire de la Loire : étude de la dynamique de la végétation de 1982 à 2014 Type de document : Article/Communication Auteurs : Mathieu Le Dez, Auteur ; Jérôme Sawtschuk, Auteur ; Frédéric Bioret, Auteur Année de publication : 2017 Note générale : Bibliographie Langues : Français (fre) Descripteur : [Vedettes matières IGN] Analyse spatiale
[Termes IGN] analyse diachronique
[Termes IGN] boisement naturel
[Termes IGN] carte de la végétation
[Termes IGN] données spatiotemporelles
[Termes IGN] dynamique de la végétation
[Termes IGN] estuaire
[Termes IGN] Loire (bassin)
[Termes IGN] plante halophile
[Termes IGN] prairieRésumé : (Auteur) L’analyse diachronique de cartes de végétation est réalisée pour caractériser les dynamiques de la végétation de l’estuaire de la Loire à différentes échelles spatiales et temporelles. Le modèle des matrices de transition est utilisé pour décrire quantitativement les dynamiques observées. Les analyses révèlent notamment la régression des prairies, le développement des roselières et des boisements ainsi que la progression des végétations halophiles. Ces résultats sont mis en relation avec l’évolution des usages sur ce territoire et les modifications du fonctionnement hydro-sédimentaire de l’estuaire. Numéro de notice : A2017-522 Affiliation des auteurs : non IGN Thématique : FORET/GEOMATIQUE Nature : Article DOI : sans En ligne : https://doi.org/10.4000/mappemonde.2097 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86539
in Mappemonde > n° 119 (janvier 2017)[article]Wetland monitoring with Global Navigation Satellite System reflectometry / Son V. Nghiem in Earth and space science, vol 4 n° 1 (January 2017)
[article]
Titre : Wetland monitoring with Global Navigation Satellite System reflectometry Type de document : Article/Communication Auteurs : Son V. Nghiem, Auteur ; Cinzia Zuffada, Auteur ; Rashmi Shah, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 16 - 39 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] delta
[Termes IGN] Ebre (bassin)
[Termes IGN] Espagne
[Termes IGN] méthane
[Termes IGN] réflectométrie par GNSS
[Termes IGN] zone humideRésumé : (auteur) Information about wetland dynamics remains a major missing gap in characterizing, understanding, and projecting changes in atmospheric methane and terrestrial water storage. A review of current satellite methods to delineate and monitor wetland change shows some recent advances, but much improved sensing technologies are still needed for wetland mapping, not only to provide more accurate global inventories but also to examine changes spanning multiple decades. Global Navigation Satellite Systems Reflectometry (GNSS-R) signatures from aircraft over the Ebro River Delta in Spain and satellite measurements over the Mississippi River and adjacent watersheds demonstrate that inundated wetlands can be identified under different vegetation conditions including a dense rice canopy and a thick forest with tall trees, where optical sensors and monostatic radars provide limited capabilities. Advantages as well as constraints of GNSS-R are presented, and the synergy with various satellite observations are considered to achieve a breakthrough capability for multidecadal wetland dynamics monitoring with frequent global coverage at multiple spatial and temporal scales. Numéro de notice : A2017-278 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1002/2016EA000194 En ligne : https://doi.org/10.1002/2016EA000194 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85302
in Earth and space science > vol 4 n° 1 (January 2017) . - pp 16 - 39[article]The protective effect of forests against rockfalls across the French Alps: Influence of forest diversity / S. Dupire in Forest ecology and management, vol 382 (15 December 2016)PermalinkComparing close-to-nature silviculture with processes in pristine forests: lessons from Central Europe / Jean-Philippe Schütz in Annals of Forest Science, vol 73 n° 4 (December 2016)PermalinkImaging the internal structure of an alpine glacier via L-band airborne SAR tomography / Stefano Tebaldini in IEEE Transactions on geoscience and remote sensing, vol 54 n° 12 (December 2016)PermalinkThe open data HELI-DEM DTM for the western alpine area: computation and publication / L. Biagi in Applied geomatics, vol 8 n° 3-4 (December 2016)PermalinkEffects of forest structure and airborne laser scanning point cloud density on 3D delineation of individual tree crowns / Kaja Kandare in European journal of remote sensing, vol 49 n° 1 (2016)PermalinkMethodology and software solutions for multicriteria evaluation of floodplain retention suitability / Rico Vogel in Cartography and Geographic Information Science, Vol 43 n° 4 (September 2016)PermalinkFast computation of general forward gravitation problems / Fabien Casenave in Journal of geodesy, vol 90 n° 7 (July 2016)PermalinkMapping and characterization of hydrological dynamics in coastal marsh using high temporal resolution Sentinel-1 images / Cécile Cazals in Remote sensing, vol 8 n° 7 (July 2016)PermalinkEstimations dendrométriques pour l’aménagement forestier à l’aide de LiDAR aéroporté : premier démonstrateur en forêts littorales dunaires / Alain Munoz in Rendez-vous techniques, n° 50 (Hiver 2016)PermalinkExpérience pratique de la réalisation du projet démonstrateur « LiDAR forestier » / Didier Canteloup in Rendez-vous techniques, n° 50 (Hiver 2016)PermalinkForest vegetation in western Romania in relation to climate variables: Does community composition reflect modelled tree species distribution? / S. Heinrichs in Annals of forest research, vol 59 n° 2 (July - December 2016)PermalinkUne frontière pour les Pyrénées : l'épisode trop méconnu de la commission topographique franco-espagnole Caro-Ornano / Jean-Yves Puyo in Cartes & Géomatique, n° 228 (juin - août 2016)PermalinkTwo new montane grassland communities from the SE Alps (N Slovenia) / Igor Dakskobler in Hacquetia, vol 15 n° 1 (June 2016)PermalinkWavelet analysis of low-frequency variability in oak tree-ring chronologies from east Central Europe / Asok K. Sen in Open geosciences, vol 8 n° 1 (January - July 2016)PermalinkLa démarche prospective au service d’un développement forestier intégré. Une étude de cas sur le massif des Landes de Gascogne / Vincent Banos in Revue forestière française, vol 68 n° 3 (mai 2016)PermalinkPaul Helbronner, le métronome de l'inutile / Daniel Léon in Pour la science, n° 463 (mai 2016)Permalink14 years of GPS tropospheric delays in the French–Italian border region : comparisons and first application in a case study / Domenico Sguerso in Applied geomatics, vol 8 n° 1 (March 2016)PermalinkBroad scale forest cover reconstruction from historical topographic maps / Dominik Kaim in Applied Geography, vol 67 (February 2016)PermalinkEffects of landscape design of forest reserves on Saproxylic beetle diversity / Christophe Bouget in Conservation biology, vol 30 n° 1 (February 2016)PermalinkImage based geo-localization in the Alps / Olivier Saurer in International journal of computer vision, vol 116 n° 3 (February 2016)PermalinkCartographier et décrire la péninsule Ibérique : l'héritage militaire français (1808-1823) / Jean-Yves Puyo in Annales de géographie, n° 707 (janvier - février 2016)PermalinkDétection à haute résolution spatiale de la desserte forestière en milieu montagneux par lidar aéroporté / Clément Mallet in Forêt entreprise, n° 226 (janvier/février 2016)PermalinkHydro-ecological monitoring of coastal marsh using high temporal resolution Sentinel-1 time serie / Cécile Cazals (2016)PermalinkPermalinkNational Forest Inventories : assessment of wood availability and use, ch. Report France : Forest resource assessment in France / Jean-Christophe Hervé (2016)PermalinkVegetation classification and biogeography of European floodplain forests and alder carrs / Jan Douda in Applied Vegetation Science, vol 19 n° 1 (January 2016)PermalinkIs Close-to-Nature Silviculture (CNS) an adequate concept to adapt forests to climate change? / Peter Spathelf in Landbauforschung, vol 65 n° 3-4 (December 2015)PermalinkPermalinkXylem and soil CO2 fluxes in a Quercus pyrenaica Willd. coppice: root respiration increases with clonal size / Roberto Salomón in Annals of Forest Science, vol 72 n° 8 (December 2015)PermalinkMapping slope movements in Alpine environments using TerraSAR-X interferometric methods / Chloé Barboux in ISPRS Journal of photogrammetry and remote sensing, vol 109 (November 2015)PermalinkInterrogations au sommet / Michel Ravelet in Géomètre, n° 2129 (octobre 2015)PermalinkMulti-method monitoring of Glacier d’Argentière dynamics / Lionel Benoit in Annals of Glaciology, vol 56 n° 70 (October 2015)PermalinkVariables related to nitrogen deposition improve defoliation models for European forests / Marco Ferretti in Annals of Forest Science, vol 72 n° 7 (October 2015)PermalinkEffet de l’exposition sur la richesse et la composition floristique des lisières forestières dans le Gâtinais oriental (Loiret) / Richard Chevalier in Revue forestière française, vol 67 n° 5 (septembre 2015)PermalinkLes espèces végétales exotiques du Massif central / Anonyme in A fleur de massif, n° 7 (septembre 2015)PermalinkImpact of the North Atlantic oscillation on Southern Europe water distribution: insights from geodetic data / Pierre Valty in Earth Interactions, vol 19 n° 10 (September 2015)PermalinkReprésenter les temporalités urbaines et commerciales : retour d'expériences européennes / Lionel Guillemot in Cartes & Géomatique, n° 225 (septembre 2015)PermalinkGenetic differentiation of European larch along an altitudinal gradient in the French Alps / Maxime Nardin in Annals of Forest Science, vol 72 n° 5 (July 2015)PermalinkThe full-scale avalanche test-site at Lautaret Pass (French Alps) / Emmanuel Thibert in Cold regions science and technology, vol 115 (July 2015)PermalinkApplication of archival aerial photogrammetry to quantify climate forcing of alpine landscapes / Natan Micheletti in Photogrammetric record, vol 30 n° 150 (June - August 2015)PermalinkThe spatiotemporal dynamics of forest–heathland communities over 60 years in Fontainebleau, France / Samira Mobaied in ISPRS International journal of geo-information, vol 4 n°2 (June 2015)Permalinkvol 72 n° 3 - May 2015 - Climate change and tree responses in Central European forests (Bulletin de Annals of Forest Science) / Thomas WohlgemuthPermalinkPhotogrammétrie et tout le reste / Anonyme in Géomatique expert, n° 104 (mai - juin 2015)PermalinkCartographie des végétations herbacées des marais littoraux à partir de données topographiques LiDAR / Sébastien Rapinel in Revue Française de Photogrammétrie et de Télédétection, n° 210 (Avril 2015)PermalinkA geographic approach for combining social media and authoritative data towards identifying useful information for disaster management / João Porto de Albuquerque in International journal of geographical information science IJGIS, vol 29 n° 4 (April 2015)Permalink