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Glacier elevation change in the Western Qilian mountains as observed by TerraSAR-X/TanDEM-X images / Qibing Zhang in Geocarto international, vol 36 n° 12 ([01/07/2021])  

Public [article]  inGeocarto international > vol 36 n° 12 [01/07/2021] . - pp 1365-1377 Titre : Glacier elevation change in the Western Qilian mountains as observed by TerraSAR-X/TanDEM-X images Type de document : Article/Communication Auteurs : Qibing Zhang, Auteur ; Shichang Kang, Auteur Année de publication : 2021 Article en page(s) : pp 1365-1377 Note générale : Bibliothèque Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] altitude [Termes IGN] changement climatique [Termes IGN] détection de changement [Termes IGN] glacier [Termes IGN] interferométrie différentielle [Termes IGN] Kansou (Chine) [Termes IGN] MNS TerraSAR & TanDEM-X [Termes IGN] montagne [Termes IGN] précipitation [Termes IGN] température de l'air [Termes IGN] Tsinghai (Chine) Résumé : (Auteur) The glaciers in the Qilian mountains are a major water resource for the arid Hexi corridor and Qaidam basin. With the climate becoming warmer and wetter, it is essential to study the glacier elevation changes in this region. We used TerraSAR-X/TanDEM-X images, SRTM DEM data and differential synthetic aperture radar interferometry (DInSAR) technology to analyse the glacier elevation change. Results show that the glacier elevation is changing at the rate of –0.35 m yr−1 in the western Qilian mountains between 2000 and 2014. The glacier elevation thinning at –0.40 m yr−1 in the southern part of this region is more severe than that in the northern part (–0.29 m yr−1). The long-term equilibrium line altitude, calculated from glacier elevation change in each elevation bin, was at 5150 m, which is equal to that inferred from glacial area distribution in each elevation bin. Glacier shrinkage is related to air temperature increasing. Numéro de notice : A2021-378 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/10106049.2019.1648563 Date de publication en ligne : 09/08/2019 En ligne : https://doi.org/10.1080/10106049.2019.1648563 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97876 [article]

Illuminating the spatio-temporal evolution of the 2008–2009 Qaidam earthquake sequence with the joint use of Insar time series and teleseismic data / Simon Daout in Remote sensing, vol 12 n° 17 (September 2020)  

Public [article]  inRemote sensing > vol 12 n° 17 (September 2020) . - 23 p. Titre : Illuminating the spatio-temporal evolution of the 2008–2009 Qaidam earthquake sequence with the joint use of Insar time series and teleseismic data Type de document : Article/Communication Auteurs : Simon Daout, Auteur ; Andreas Steinberg, Auteur ; Marius Paul Isken, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : 23 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] analyse spatio-temporelle [Termes IGN] données géodésiques [Termes IGN] faille géologique [Termes IGN] image Envisat [Termes IGN] image radar moirée [Termes IGN] inférence [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] séisme [Termes IGN] série temporelle [Termes IGN] sismologie [Termes IGN] Tsinghai (Chine) Résumé : (auteur) Inferring the geometry and evolution of an earthquake sequence is crucial to understand how fault systems are segmented and interact. However, structural geological models are often poorly constrained in remote areas and fault inference is an ill-posed problem with a reliability that depends on many factors. Here, we investigate the geometry of the Mw 6.3 2008 and 2009 Qaidam earthquakes, in northeast Tibet, by combining InSAR time series and teleseismic data. We conduct a multi-array back-projection analysis from broadband teleseismic data and process three overlapping Envisat tracks covering the two earthquakes to extract the spatio-temporal evolution of seismic ruptures. We then integrate both geodetic and seismological data into a self-consistent kinematic model of the earthquake sequence. Our results constrain the depth and along-strike segmentation of the thrust-faulting sequence. The 2008 earthquake ruptured a ∼32° north-dipping fault that roots under the Olongbulak pop-up structure at ∼12 km depth and fault slip evolved post-seismically in a downdip direction. The 2009 earthquake ruptured three south-dipping high-angle thrusts and propagated from ∼9 km depth to the surface and bilaterally along the south-dipping segmented 55–75° high-angle faults of the Olonbulak pop-up structure that displace basin deformed sedimentary sequences above Paleozoic bedrock. Our analysis reveals that the inclusion of the post-seismic afterslip into modelling is beneficial in the determination of fault geometry, while teleseismic back-projection appears to be a robust tool for identifying rupture segmentation for moderate-sized earthquakes. These findings support the hypothesis that the Qilian Shan is expanding southward along a low-angle décollement that partitions the oblique convergence along multiple flower and pop-up structures. Numéro de notice : A2020-599 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.3390/rs12172850 Date de publication en ligne : 02/09/2020 En ligne : https://doi.org/10.3390/rs12172850 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95947 [article]

Adjustment computation of HASM : a high-accuracy and high speed method / T. Yue in International journal of geographical information science IJGIS, vol 24 n°11-12 (december 2010)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 24 n°11-12 (december 2010) . - pp 1725 - 1743 Titre : Adjustment computation of HASM : a high-accuracy and high speed method Type de document : Article/Communication Auteurs : T. Yue, Auteur ; Shuo Wang, Auteur Année de publication : 2010 Article en page(s) : pp 1725 - 1743 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique [Termes IGN] compensation par modèles [Termes IGN] Kansou (Chine) [Termes IGN] modèle numérique de surface [Termes IGN] modélisation 2D [Termes IGN] Setchouan (Chine) [Termes IGN] surface (géométrie) [Termes IGN] test de performance [Termes IGN] traitement de données localisées [Termes IGN] Tsinghai (Chine) [Termes IGN] visualisation simultanée Résumé : (Auteur) We developed a method for high-accuracy surface modeling (HASM) in terms of the fundamental theorem of surfaces, which has theoretically found a solution for error problems. However, the computing speed of HASM was too slow to be widely applied in practice. Thus, adjustment computation of HASM (HASM-AC) is developed in this article. For comparatively testing HASM-AC accuracy, a mathematical surface is first selected so that the true value is able to be predetermined to avoid uncontrollable data errors. The numerical test indicates that HASM-AC has the highest accuracy and its accuracy is 20.67, 15.67, and 14.67 times higher than the inverse distance weighting (IDW), kriging, and spline, respectively. Then, a 0.4 km times 0.5 km rectangular area is used to test the effects of different spatial resolutions and sampling intervals on accuracy. This real-world test demonstrates that HASM-AC accuracy increases at a much better and stable pace as the spatial resolution becomes finer and sampling intervals get shorter, compared to the classic methods. Finally, the computing speed is tested in an area with 6000 times 6000 grid cells where Qinghai, Gansu, and Sichuan provinces meet. The computing speed of HASM-AC is 11, 8, and 563 times faster than IDW, spline, and kriging, respectively, which makes HASM-AC able to process data in a huge size and make real-time visualization realizable. In short, HASM-AC performs best in both the numerical and real-world tests. Numéro de notice : A2010-550 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/13658810903569580 En ligne : https://doi.org/10.1080/13658810903569580 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30742 [article]

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