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Recognition of crevasses with high-resolution digital elevation models: Application of geomorphometric modeling and texture analysis / Olga T. Ishalina in Transactions in GIS, vol 25 n° 5 (October 2021)  

Public [article]  inTransactions in GIS > vol 25 n° 5 (October 2021) . - pp 2529 - 2552 Titre : Recognition of crevasses with high-resolution digital elevation models: Application of geomorphometric modeling and texture analysis Type de document : Article/Communication Auteurs : Olga T. Ishalina, Auteur ; Dimitri P. Bliakharskii, Auteur ; Igor V. Florinsky, Auteur Année de publication : 2021 Article en page(s) : pp 2529 - 2552 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] analyse comparative [Termes IGN] analyse texturale [Termes IGN] Antarctique [Termes IGN] crevasse [Termes IGN] glacier [Termes IGN] image à haute résolution [Termes IGN] image captée par drone [Termes IGN] modèle numérique de surface [Termes IGN] texture d'image Résumé : (auteur) Crevasses—cracks in glaciers and ice sheets—pose a danger to polar researchers and glaciologists. We compare the capabilities of two techniques—geomorphometric modeling and texture analysis—to recognize open and hidden crevasses using high-resolution digital elevation models (DEMs) generated from images collected by an unmanned aerial system (UAS). The first technique includes derivation of local morphometric variables; the second includes calculation of the Haralick texture features. The study area is represented by the first 30 km of a sledge route between the Progress and Vostok polar stations, East Antarctica. The UAS survey was performed by a Geoscan 201 Geodesy UAS. For the sledge route area, DEMs with resolutions of 0.25, 0.5, and 1 m were generated. Models of 12 morphometric variables and 11 texture features were derived from the DEMs. In terms of crevasse recognition, the most informative morphometric variable and texture feature was horizontal curvature and inverse difference moment, respectively. In most cases, derivation and mapping of these variables allow one to recognize crevasses wider than 3 m; narrower crevasses can be recognized for lengths from 500 m. For crevasse recognition, the geomorphometric modeling and the Haralick texture analysis can complement each other. Numéro de notice : A2021-122 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/tgis.12790 Date de publication en ligne : 06/07/2021 En ligne : https://doi.org/10.1111/tgis.12790 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99303 [article]

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]

Discovery of new colonies by Sentinel2 reveals good and bad news for emperor penguins / Peter T. Fretwell in Remote sensing in ecology and conservation, vol 7 n° 2 (June 2021)  

Public [article]  inRemote sensing in ecology and conservation > vol 7 n° 2 (June 2021) . - pp 139 - 153 Titre : Discovery of new colonies by Sentinel2 reveals good and bad news for emperor penguins Type de document : Article/Communication Auteurs : Peter T. Fretwell, Auteur ; Philip N. Trathan, Auteur Année de publication : 2021 Article en page(s) : pp 139 - 153 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] Antarctique [Termes IGN] Aves [Termes IGN] image Sentinel-MSI Mots-clés libres : manchot empereur  Aptenodytes forsteri Résumé : (auteur) The distribution of emperor penguins is circumpolar, with 54 colony locations currently reported of which 50 are currently extant as of 2019. Here we report on eight newly discovered colonies and confirm the rediscovery of three breeding sites, only previously reported in the era before Very High Resolution satellite imagery was available, making a total of 61 breeding locations. This represents an increase of ~20% in the number of breeding sites, but, as most of the colonies appear to be small, they may only increase the total population by around 5–10%. The discoveries have been facilitated by the use of Sentinel2 satellite imagery, which has a higher resolution and more efficient search mechanism than the Landsat data previously used to search for colonies. The small size of these new colonies indicates that considerations of reproductive output in relation to metabolic rate during huddling is likely to be of interest. Some of the colonies exist in offshore habitats, something not previously reported for emperor penguins. Comparison with recent modelling results show that the geographic locations of all the newly found colonies are in areas likely to be highly vulnerable under business-as-usual greenhouse gas emissions scenarios, suggesting that population decreases for the species will be greater than previously thought. Numéro de notice : A2021-732 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1002/rse2.176 Date de publication en ligne : 04/08/2020 En ligne : https://doi.org/10.1002/rse2.176 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98678 [article]

Time-series snowmelt detection over the Antarctic using Sentinel-1 SAR images on Google Earth Engine / Dong Liang in Remote sensing of environment, Vol 256 (April 2020)  

Public [article]  inRemote sensing of environment > Vol 256 (April 2020) . - n° 112318 Titre : Time-series snowmelt detection over the Antarctic using Sentinel-1 SAR images on Google Earth Engine Type de document : Article/Communication Auteurs : Dong Liang, Auteur ; Huadong Guo, Auteur ; Lu Zhang, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 112318 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] albedo [Termes IGN] Antarctique [Termes IGN] calotte glaciaire [Termes IGN] changement climatique [Termes IGN] coefficient de rétrodiffusion [Termes IGN] distribution spatiale [Termes IGN] fonte des glaces [Termes IGN] Google Earth Engine [Termes IGN] image radar moirée [Termes IGN] image Sentinel-SAR [Termes IGN] montée du niveau de la mer [Termes IGN] série temporelle Résumé : (auteur) The Antarctic ice sheet is an important mass of glacier ice. It is particularly sensitive to climate change, and the flow of Antarctica's inland glaciers into the sea, accelerated by collapsing ice shelves, threatens global sea level rise. The amount of snowmelt on the surface of the ice sheet is an important metric for accurately assessing surface material loss and albedo change, which affect the stability of the ice sheet. This study proposes a framework for quickly extracting time-series freeze-thaw information at the continental scale and 40 m resolution by taking advantage of the huge amount of synthetic aperture radar (SAR) data acquired by Sentinel-1 satellites over the Antarctic, available for rapid processing on Google Earth Engine. Co-orbit normalization is used in the proposed framework to establish a unified standard of judgement by reducing the variations in the backscattering coefficient introduced by observation geometry, terrain fluctuations, and melt conditions between images acquired at different times. We implemented the framework to produce a massive dataset of both monthly freeze-thaw information over the Antarctic and higher temporal resolution freeze-thaw information for the Larsen C ice shelf from 2015 to 2019, with overall accuracies of 93% verified by a manual visual interpretation method and 84% evaluated from automatic weather station temperatures. Due to its effectiveness and robustness, the framework can be used to analyse the spatiotemporal distribution of snowmelt, the change in melt area, and anomalous melt events in Antarctica, especially those in Larsen C caused by foehn wind. Numéro de notice : A2021-477 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1016/j.rse.2021.112318 Date de publication en ligne : 10/02/2021 En ligne : https://doi.org/10.1016/j.rse.2021.112318 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97117 [article]

Mitigating high latitude ionospheric scintillation effects on GNSS Precise Point Positioning exploiting 1-s scintillation indices / Kai Guo in Journal of geodesy, vol 95 n° 3 (March 2021)  

Public [article]  inJournal of geodesy > vol 95 n° 3 (March 2021) . - n° 30 Titre : Mitigating high latitude ionospheric scintillation effects on GNSS Precise Point Positioning exploiting 1-s scintillation indices Type de document : Article/Communication Auteurs : Kai Guo, Auteur ; Sreeja Vadakke Veettil, Auteur ; Brian Jerald Weaver, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 30 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] Antarctique [Termes IGN] atténuation du signal [Termes IGN] Canada [Termes IGN] erreur de positionnement [Termes IGN] latitude [Termes IGN] positionnement par GNSS [Termes IGN] positionnement ponctuel précis [Termes IGN] récepteur GNSS [Termes IGN] scintillation [Termes IGN] tempête magnétique Résumé : (auteur) Ionospheric scintillation refers to rapid and random fluctuations in radio frequency signal intensity and phase, which occurs more frequently and severely at high latitudes under strong solar and geomagnetic activity. As one of the most challenging error sources affecting Global Navigation Satellite System (GNSS), scintillation can significantly degrade the performance of GNSS receivers, thereby leading to increased positioning errors. This study analyzes Global Positioning System (GPS) scintillation data recorded by two ionospheric scintillation monitoring receivers operational, respectively, in the Arctic and northern Canada during a geomagnetic storm in 2019. A novel approach is proposed to calculate 1-s scintillation indices. The 1-s receiver tracking error variances are then estimated, which are further used to mitigate the high latitude scintillation effects on GPS Precise Point Positioning. Results show that the 1-s scintillation indices can describe the signal fluctuations under scintillation more accurately. With the mitigation approach, the 3D positioning error is greatly reduced under scintillation analyzed in this study. Additionally, the 1-s tracking error variance achieves a better performance in scintillation mitigation compared with the previous approach which exploits 1-min tracking error variance estimated by the commonly used 1-min scintillation indices. This work is relevant for a better understanding of the high latitude scintillation effects on GNSS and is also beneficial for developing scintillation mitigation tools for GNSS positioning. Numéro de notice : A2021-222 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01475-y Date de publication en ligne : 22/02/2021 En ligne : https://doi.org/10.1007/s00190-021-01475-y Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97191 [article]

Glaciers and the polar environment / Masaki Kanao (2021)    

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Recent changes in two outlet glaciers in the Antarctic Peninsula using multi-temporal Landsat and Sentinel-1 data / Carolina L. Simões in Geocarto international, vol 35 n° 11 ([01/08/2020])  

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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)  

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Inside the ice shelf: using augmented reality to visualise 3D lidar and radar data of Antarctica / Alexandra L. Boghosian in Photogrammetric record, vol 34 n° 168 (December 2019)  

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Analysis of the usability of mobile laser scanning data in snowy conditions / Mathilde Letard (2019) 

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Dumont d’Urville ITRF co-location site survey Antarctica / Thomas Donal (2019)

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Evaluation of terrestrial and airborne gravity data over Antarctica : a generic approach / Philipp Zingerle in Journal of geodetic science, vol 9 n° 1 (January 2019)  

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Global IWV trends and variability in atmospheric reanalyses and GPS observations / Ana-Claudia Bernardes Parracho in Atmospheric chemistry and physics, vol 18 n° 22 ([01/11/2018])  

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

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Improved geometric modeling of 1960s KH-5 ARGON satellite images for regional Antarctica applications / Wenkai Ye in Photogrammetric Engineering & Remote Sensing, PERS, vol 83 n° 7 (July 2017)  

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