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Comparison of polar ionospheric behavior at Arctic and Antarctic regions for improved satellite-based positioning / Arun Kumar Singh in Journal of applied geodesy, vol 15 n° 3 (July 2021)  

Public [article]  inJournal of applied geodesy > vol 15 n° 3 (July 2021) . - pp 269 - 277 Titre : Comparison of polar ionospheric behavior at Arctic and Antarctic regions for improved satellite-based positioning Type de document : Article/Communication Auteurs : Arun Kumar Singh, Auteur Année de publication : 2021 Article en page(s) : pp 269 - 277 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] amplitude [Termes IGN] Antarctique [Termes IGN] Arctique [Termes IGN] champ géomagnétique [Termes IGN] ionosphère [Termes IGN] magnétosphère [Termes IGN] phase [Termes IGN] pôle [Termes IGN] positionnement par GNSS [Termes IGN] retard ionosphèrique [Termes IGN] scintillation [Termes IGN] teneur totale en électrons [Termes IGN] variation temporelle Résumé : (Auteur) In this paper, we investigate the hemispheric symmetric and asymmetric characteristics of ionospheric total electron content (TEC) and its dependency on the interplanetary magnetic field (IMF) in the northern and southern polar ionosphere. The changes in amplitude and phase scintillation are also probed through Global Ionospheric Scintillation and TEC monitoring (GISTM) systems recordings at North pole [Himadri station; Geographic 78°55′ N, 11°56′ E] and South pole [Maitri station; Geographic 70°46′ S 11°44′ E]. Observations show the range of %TEC variability being relatively more over Antarctic region (−40 % to 60 %) than Arctic region (−25 % to 25 %), corroborating the role of the dominant solar photoionization production process. Our analysis confirms that TEC variation at polar latitudes is a function of magnetosphere-ionosphere coupling, depending on interplanetary magnetic field (IMF) orientation and magnitude in the X ( Bx), Y ( By), and Z ( Bz) plane. Visible enhancement in TEC is noticed in the northern polar latitude when Bx6nT and Bz>0 whereas the southern polar latitude perceives TEC enhancements with Bx>0, −6nT Numéro de notice : A2021-469 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2021-0033 date de publication en ligne : 22/06/2021 En ligne : https://doi.org/10.1515/jag-2021-0033 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98107 [article]

Rapid ecosystem change at the southern limit of the Canadian Arctic, Torngat Mountains National Park / Emma L. Davis in Remote sensing, vol 13 n° 11 (June-1 2021)  

Public [article]  inRemote sensing > vol 13 n° 11 (June-1 2021) . - n° 2085 Titre : Rapid ecosystem change at the southern limit of the Canadian Arctic, Torngat Mountains National Park Type de document : Article/Communication Auteurs : Emma L. Davis, Auteur ; Andrew Trant, Auteur ; Robert G. Way, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 2085 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] arbuste [Termes IGN] Arctique [Termes IGN] Canada [Termes IGN] changement climatique [Termes IGN] classification par forêts aléatoires [Termes IGN] détection de changement [Termes IGN] écosystème [Termes IGN] écotone [Termes IGN] géostatistique [Termes IGN] image Landsat-ETM+ [Termes IGN] image Landsat-OLI [Termes IGN] image Terra-MODIS [Termes IGN] modèle de simulation [Termes IGN] Normalized Difference Vegetation Index [Termes IGN] parc naturel national [Termes IGN] régression logistique [Termes IGN] surveillance de la végétation [Termes IGN] toundra Résumé : (auteur) Northern protected areas guard against habitat and species loss but are themselves highly vulnerable to environmental change due to their fixed spatial boundaries. In the low Arctic, Torngat Mountains National Park (TMNP) of Canada, widespread greening has recently occurred alongside warming temperatures and regional declines in caribou. Little is known, however, about how biophysical controls mediate plant responses to climate warming, and available observational data are limited in temporal and spatial scope. In this study, we investigated the drivers of land cover change for the 9700 km2 extent of the park using satellite remote sensing and geostatistical modelling. Random forest classification was used to hindcast and simulate land cover change for four different land cover types from 1985 to 2019 with topographic and surface reflectance imagery (Landsat archive). The resulting land cover maps, in addition to topographic and biotic variables, were then used to predict where future shrub expansion is likely to occur using a binomial regression framework. Land cover hindcasts showed a 235% increase in shrub and a 105% increase in wet vegetation cover from 1985/89 to 2015/19. Shrub cover was highly persistent and displaced wet vegetation in southern, low-elevation areas, whereas wet vegetation expanded to formerly dry, mid-elevations. The predictive model identified both biotic (initial cover class, number of surrounding shrub neighbors), and topographic variables (elevation, latitude, and distance to the coast) as strong predictors of future shrub expansion. A further 51% increase in shrub cover is expected by 2039/43 relative to 2014 reference data. Establishing long-term monitoring plots within TMNP in areas where rapid vegetation change is predicted to occur will help to validate remote sensing observations and will improve our understanding of the consequences of change for biotic and abiotic components of the tundra ecosystem, including important cultural keystone species. Numéro de notice : A2021-442 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.3390/rs13112085 date de publication en ligne : 26/05/2021 En ligne : https://doi.org/10.3390/rs13112085 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97832 [article]

Understanding the synergies of deep learning and data fusion of multispectral and panchromatic high resolution commercial satellite imagery for automated ice-wedge polygon detection / Chandi Witharana in ISPRS Journal of photogrammetry and remote sensing, vol 170 (December 2020)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 170 (December 2020) . - pp 174-191 Titre : Understanding the synergies of deep learning and data fusion of multispectral and panchromatic high resolution commercial satellite imagery for automated ice-wedge polygon detection Type de document : Article/Communication Auteurs : Chandi Witharana, Auteur ; Md Abul Ehsan Bhuiyan, Auteur ; Anna K. Liljedahl, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : pp 174-191 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] algorithme de fusion [Termes IGN] apprentissage profond [Termes IGN] Arctique [Termes IGN] artefact [Termes IGN] classification par réseau neuronal convolutif [Termes IGN] détection automatique [Termes IGN] fusion d'images [Termes IGN] glace [Termes IGN] image à haute résolution [Termes IGN] pergélisol [Termes IGN] texture d'image Résumé : (Auteur) The utility of sheer volumes of very high spatial resolution (VHSR) commercial imagery in mapping the Arctic region is new and actively evolving. Commercial satellite sensors typically record image data in low-resolution multispectral (MS) and high-resolution panchromatic (PAN) mode. Spatial resolution is needed to accurately describe feature shapes and textural patterns, such as ice-wedge polygons (IWPs) that are rapidly transforming surface features due to degrading permafrost, while spectral resolution allows capturing of land-use and land-cover types. Data fusion, the process of combining PAN and MS images with complementary characteristics often serves as an integral component of remote sensing mapping workflows. The fusion process generates spectral and spatial artifacts that may affect the classification accuracies of subsequent automated image analysis algorithms, such as deep learning (DL) convolutional neural nets (CNN). We employed a detailed multidimensional assessment to understand the performances of an array of eight application-oriented data fusion algorithms when applied to VHSR image scenes for DLCNN-based mapping of ice-wedge polygons. Our findings revealed the scene dependency of data fusion algorithms and emphasized the need for careful selection of the proper algorithm. Results suggested that the fusion algorithms that preserve spatial character of original PAN imagery favor the DLCNN model performances. The choice of fusion approach needs to be considered of equal importance to the required training dataset for successful applications using DLCNN on VHRS imagery in order to enable an accurate mapping effort of permafrost thaw across the Arctic region. Numéro de notice : A2020-705 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2020.10.010 date de publication en ligne : 01/11/2020 En ligne : https://doi.org/10.1016/j.isprsjprs.2020.10.010 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96232 [article]

Arctic tsunamis threaten coastal landscapes and communities – survey of Karrat Isfjord 2017 tsunami effects in Nuugaatsiaq, western Greenland / Mateusz C. Strzelecki in Natural Hazards and Earth System Sciences, vol 20 n° 9 (September 2020)  

Public [article]  inNatural Hazards and Earth System Sciences > vol 20 n° 9 (September 2020) . - pp 2521 - 2534 Titre : Arctic tsunamis threaten coastal landscapes and communities – survey of Karrat Isfjord 2017 tsunami effects in Nuugaatsiaq, western Greenland Type de document : Article/Communication Auteurs : Mateusz C. Strzelecki, Auteur ; Marek W. Jaskólski, Auteur Année de publication : 2020 Article en page(s) : pp 2521 - 2534 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] analyse du paysage [Termes IGN] Arctique [Termes IGN] changement climatique [Termes IGN] dégradation des sols [Termes IGN] détection de changement [Termes IGN] effondrement de terrain [Termes IGN] érosion côtière [Termes IGN] fjord [Termes IGN] Groenland [Termes IGN] inondation [Termes IGN] littoral [Termes IGN] paysage [Termes IGN] risque naturel [Termes IGN] toundra [Termes IGN] tsunami Résumé : (auteur) On the 17 June 2017, a massive landslide which mobilized 35–58 million m3 of material entered the Karrat Isfjord in western Greenland. It triggered a tsunami wave with a runup height exceeding 90 m close to the landslide, ca. 50 m on the opposite shore of the fjord. The tsunami travelled ca. 32 km along the fjord and reached the settlement of Nuugaatsiaq with ca. 1–1.5 m high waves which flooded the terrain up to 9 m a.s.l. (above sea level). Tsunami waves were powerful enough to destroy the community infrastructure, impact fragile coastal tundra landscape, and unfortunately injure several inhabitants and cause four deaths. Our field survey carried out 25 months after the event results in documentation of the previously unreported scale of damage in the settlement (ca. 48 % of infrastructure objects including houses and administration buildings were destroyed by the tsunami). We have observed a recognizable difference in the concentration of tsunami deposit accumulations between areas of the settlement overwashed by the wave and areas of runup and return flow. The key tsunami effects preserved in the coastal landscape were eroded coastal bluffs, gullied and dissected edges of cliffed coast in the harbour, and tundra vegetation compressed by boulders or icebergs rafted onshore during the event. Numéro de notice : A2020-612 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.5194/nhess-20-2521-2020 date de publication en ligne : 24/09/2020 En ligne : https://doi.org/10.5194/nhess-20-2521-2020 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95979 [article]

Using real polar ground gravimetry data to solve the GOCE polar gap problem in satellite-only gravity field recovery / Biao Lu in Journal of geodesy, Vol 94 n°3 (March 2020)  

Public [article]  inJournal of geodesy > Vol 94 n°3 (March 2020) Titre : Using real polar ground gravimetry data to solve the GOCE polar gap problem in satellite-only gravity field recovery Type de document : Article/Communication Auteurs : Biao Lu, Auteur ; Christoph Förste, Auteur ; Franz Barthelmes, Auteur ; et al., Auteur Année de publication : 2020 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] anomalie de pesanteur [Termes IGN] Antarctique [Termes IGN] Arctique [Termes IGN] champ de gravitation [Termes IGN] données GOCE [Termes IGN] données GRACE [Termes IGN] Earth Gravity Model 2008 [Termes IGN] filtrage d'information [Termes IGN] levé gravimétrique [Termes IGN] modèle de géopotentiel [Termes IGN] zone polaire Résumé : (auteur) With the successful completion of European Space Agency (ESA)’s PolarGAP campaign, ground gravity data are now available for both polar regions. Therefore, it is now possible to solve the GOCE polar gap problem in satellite-only gravity field recovery by using additional polar ground gravity data instead of some regularization methods. However, ground gravimetry data need to be filtered to remove the short-wavelength information beyond a certain harmonic degree to avoid spectral leakage when inferring satellite-only gravity field models. For the Arctic, the ArcGP data set was successfully applied when inferring the high-resolution gravity field model EGM2008 which could be used for this filtering there. For Antarctica, a combination of latest airborne gravimetry data from ESA’s PolarGap campaign and some previous gravity data was recently published which was irregularly distributed in space and still had some small gaps within the GOCE south polar gap. Therefore, we proposed a point mass modeling method for this filtering which was similar to the way using EGM2008 for such filtering to the ground gravity data in the Arctic. Furthermore, a variance component estimation was applied to combine the normal equations from the different sources to build a global gravity field model called IGGT_R1C. Then, this model’s accuracy was evaluated by comparison with other gravity field models in terms of difference degree amplitudes, gravity anomaly differences as well as external checking by obit adjustment and gravity data in the GOCE polar gap areas. This gravity field model performed well globally according to these checking results; especially, the RMS of the residuals between the filtered gravity data and that calculated from IGGT_R1C was the smallest (2.6 mGal in the Arctic and 5.4 mGal in Antarctica) compared with that of the relevant satellite-only gravity field models, e.g., GOCO05s. Therefore, the disturbing impact of the GOCE polar data gap problem could be solved by adding the polar ground gravity data. Numéro de notice : A2020-155 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01361-z date de publication en ligne : 25/02/2020 En ligne : https://doi.org/10.1007/s00190-020-01361-z Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94805 [article]

Caractérisation du manteau neigeux arctique, suivi climatique et télédétection micro-onde / Céline Vargel (2020)  

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Non-stationary response of tree growth to climate trends along the Arctic margin / Annika Hofgaard in Ecosystems, vol 22 n° 2 (March 2019)  

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Remote sensing of environmental changes in cold regions / Jinyang Du (2019)  

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Association rules-based multivariate analysis and visualization of spatiotemporal climate data / Feng Wang in ISPRS International journal of geo-information, vol 7 n° 7 (July 2018)  

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Comparison of total water vapour content in the Arctic derived from GNSS, AIRS, MODIS and SCIAMACHY / Dunya Alraddawi in Atmospheric measurement techniques, vol 11 n° 5 (May 2018)  

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Enhanced MODIS atmospheric total water vapour content trends in response to Arctic amplification / Dunya Alraddawi in Atmosphere, vol 8 n° 12 (December 2017)  

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PolarGlobe : A web-wide virtual globe system for visualizing multidimensional, time-varying, big climate data / Wenwen Li in International journal of geographical information science IJGIS, vol 31 n° 7-8 (July - August 2017)  

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Northern exposure / Ingo Simonis in GEO: Geoconnexion international, vol 15 n° 6 (June 2016)

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Landscape controls over major nutrients and primary productivity of Arctic lakes / P. Pathak in Cartography and Geographic Information Science, vol 39 n° 4 (October 2012)  

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Producing an indigenous knowledge Web GIS for Arctic Alaska communities: Challenges, successes, and lessons learned / W. Eisner in Transactions in GIS, vol 16 n° 1 (February 2012)  

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