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Dense mantle flows periodically spaced below ocean basins / Isabelle Panet in Earth and planetary science letters, vol 594 (15 September 2022)  

Public [article]  inEarth and planetary science letters > vol 594 (15 September 2022) . - n° 117745 Titre : Dense mantle flows periodically spaced below ocean basins Type de document : Article/Communication Auteurs : Isabelle Panet , Auteur ; Marianne Greff-Lefftz, Auteur ; Barbara Romanowicz, Auteur Année de publication : 2022 Projets : Université de Paris / Clerici, Christine Article en page(s) : n° 117745 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] champ de pesanteur terrestre [Termes IGN] convection [Termes IGN] déformation de la croute terrestre [Termes IGN] dynamique des fluides [Termes IGN] fond marin [Termes IGN] Indien (océan) [Termes IGN] lithosphère [Termes IGN] manteau terrestre [Termes IGN] Pacifique (océan) Résumé : (auteur) Understanding mantle flow is key to elucidate how deep Earth dynamics relate to tectonics at the global scale. The convective mass transport is reflected in lateral variations of the gravity field, seismic velocities, as well as deformations of the Earth's surface. Yet, upper to mid-mantle dynamics have been difficult to constrain at the medium scales of thousands of km. Here, we analyze the second-order horizontal derivatives of seafloor topography and of the gravity potential over the Pacific and Northern Indian ocean basins, and provide evidence for periodic undulations of 1600-2000 km wavelength in both signals, elongated along the direction of absolute plate motion. We investigate potential crustal and lithospheric sources and show that at least part of this signal must originate below the lithosphere, with alignments of sub-lithospheric upper mantle mass excess below seafloor lows. Furthermore, we find that these alignments coincide geographically over wide areas with similarly periodic slow seismic velocity fingers located at upper mantle depths. These two fields may thus record an intermediate scale of mantle convection below ocean basins, which cannot be explained by purely thermal convection and requires instead lateral variations in composition in the upper mantle. Elucidating the nature of the detected mass excess sources coincident with the slow seismic velocities calls for a joint dynamical modeling of all observations in a thermo-chemical context. Numéro de notice : A2022-692 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.epsl.2022.117745 En ligne : https://doi.org/10.1016/j.epsl.2022.117745 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101809 [article]

Analytical method for high-precision seabed surface modelling combining B-spline functions and Fourier series / Tyler Susa in Marine geodesy, vol 45 n° 5 (September 2022)  

Public [article]  inMarine geodesy > vol 45 n° 5 (September 2022) . - pp 435 - 461 Titre : Analytical method for high-precision seabed surface modelling combining B-spline functions and Fourier series Type de document : Article/Communication Auteurs : Tyler Susa, Auteur Année de publication : 2022 Article en page(s) : pp 435 - 461 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] bathymétrie [Termes IGN] classification par forêts d'arbres décisionnels [Termes IGN] données d'entrainement (apprentissage automatique) [Termes IGN] Extreme Gradient Machine [Termes IGN] fond marin [Termes IGN] image Sentinel-MSI [Termes IGN] littoral [Termes IGN] modèle numérique de surface [Termes IGN] modélisation [Termes IGN] Porto Rico [Termes IGN] profondeur [Termes IGN] réflectance Résumé : (auteur) Accurate charting of nearshore bathymetry is critical to the safe and dependable use of coastal waterways frequented by the trading, fishing, tourism, and ocean energy industries. The accessibility of satellite imagery and the availability of various satellite-derived bathymetry (SDB) techniques have provided a cost-effective alternative to traditional in-situ bathymetric surveys. Furthermore, improved algorithms and the advancement of machine learning models have provided opportunity for higher quality bathymetric derivations. However, to date the relative accuracy and performance between traditional physics-based techniques, improved physics-based methods, and machine learning ensemble models have not been adequately quantified. In this study, nearshore bathymetry is derived from Sentinel-2 satellite imagery near La Parguera, Puerto Rico utilizing a traditional band-ratio algorithm, a band-ratio switching method, a random forest machine learning model, and the XGBoost machine learning model. The machine learning models returned comparable results and were markedly more accurate relative to other techniques; however, both machine learning models required an extensive training dataset. All models were constrained by environmental influences and image spatial resolution, which were assessed to be the limiting factors for routine use of satellite-derived bathymetry as a reliable method for hydrographic surveying. Numéro de notice : A2022-609 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01490419.2022.2064572 Date de publication en ligne : 04/05/2022 En ligne : https://doi.org/10.1080/01490419.2022.2064572 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101392 [article]

How can Sentinel-2 contribute to seagrass mapping in shallow, turbid Baltic Sea waters? / Katja Kuhwald in Remote sensing in ecology and conservation, vol 8 n° 3 (June 2022)  

Public [article]  inRemote sensing in ecology and conservation > vol 8 n° 3 (June 2022) . - pp 328 - 346 Titre : How can Sentinel-2 contribute to seagrass mapping in shallow, turbid Baltic Sea waters? Type de document : Article/Communication Auteurs : Katja Kuhwald, Auteur ; Jens Schneider Von Deimling, Auteur ; Philipp Schubert, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : pp 328 - 346 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] Allemagne [Termes IGN] Baltique, mer [Termes IGN] carte thématique [Termes IGN] classification par forêts d'arbres décisionnels [Termes IGN] eaux côtières [Termes IGN] fond marin [Termes IGN] herbier marin [Termes IGN] image aérienne [Termes IGN] image Sentinel-MSI [Termes IGN] lidar bathymétrique [Termes IGN] turbidité des eaux Résumé : (auteur) Seagrass meadows are one of the most important benthic habitats in the Baltic Sea. Nevertheless, spatially continuous mapping data of Zostera marina, the predominant seagrass species in the Baltic Sea, are lacking in the shallow coastal waters. Sentinel-2 turned out to be valuable for mapping coastal benthic habitats in clear waters, whereas knowledge in turbid waters is rare. Here, we transfer a clear water mapping approach to turbid waters to assess how Sentinel-2 can contribute to seagrass mapping in the Western Baltic Sea. Sentinel-2 data were atmospherically corrected using ACOLITE and subsequently corrected for water column effects. To generate a data basis for training and validating random forest classification models, we developed an upscaling approach using video transect data and aerial imagery. We were able to map five coastal benthic habitats: bare sand (25 km²), sand dominated (16 km²), seagrass dominated (7 km²), dense seagrass (25 km²) and mixed substrates with red/ brown algae (3.5 km²) in a study area along the northern German coastline. Validation with independent data pointed out that water column correction does not significantly improve classification results compared to solely atmospherically corrected data (balanced overall accuracies ~0.92). Within optically shallow waters (0–4 m), per class and overall balanced accuracies (>0.82) differed marginally depending on the water depth. Overall balanced accuracy became worse ( Numéro de notice : A2022-499 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1002/rse2.246 Date de publication en ligne : 07/12/2021 En ligne : https://doi.org/10.1002/rse2.246 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100995 [article]

Framework for automatic coral reef extraction using Sentinel-2 image time series / Qizhi Zhang in Marine geodesy, vol 45 n° 3 (May 2022)  

Public [article]  inMarine geodesy > vol 45 n° 3 (May 2022) . - pp 195 - 231 Titre : Framework for automatic coral reef extraction using Sentinel-2 image time series Type de document : Article/Communication Auteurs : Qizhi Zhang, Auteur ; Jian Zhang, Auteur ; Liang Cheng, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : pp 195 - 231 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] Chine [Termes IGN] extraction de traits caractéristiques [Termes IGN] filtrage de points [Termes IGN] filtrage spatiotemporel [Termes IGN] image Sentinel-MSI [Termes IGN] mesure de similitude [Termes IGN] nébulosité [Termes IGN] récif corallien [Termes IGN] série temporelle Résumé : (auteur) Using supervised and unsupervised classification on a single image to extract coral reef extent results in missing data and wrong extraction results. To improve the accuracy of coral reef extraction, this study proposes a novel technical framework for automatic coral reef extraction based on an image filtering strategy and spatiotemporal similarity measurements of pixel-level Sentinel-2 image time series. This method was applied to the Anda Reef, Daxian Reef, and Nanhua Reef, China, using 1464 Sentinel-2 images obtained from 2015–2020. Sentinel-2 images were automatically selected considering space, time, cloud cover, and image entropy after atmospheric correction. With the binary classification measurement standard using the digitization coral reef results of the Sentinel-2 images as the true value, the time series established by the modified normalized difference water index demonstrated high robustness and accuracy. Analyzing the time series curves of the coral reef and deep water verified that the spatiotemporal similarity measurement of this framework can stably extract the boundaries of the coral reef. Numéro de notice : A2022-353 Affiliation des auteurs : non IGN Thématique : IMAGERIE/INFORMATIQUE Nature : Article DOI : 10.1080/01490419.2022.2051648 Date de publication en ligne : 28/03/2022 En ligne : https://doi.org/10.1080/01490419.2022.2051648 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100550 [article]

Evaluating the 3D integrity of underwater structure from motion workflows / Ian M. Lochhead in Photogrammetric record, vol 37 n° 177 (March 2022)  

Public [article]  inPhotogrammetric record > vol 37 n° 177 (March 2022) . - pp 35 - 60 Titre : Evaluating the 3D integrity of underwater structure from motion workflows Type de document : Article/Communication Auteurs : Ian M. Lochhead, Auteur Année de publication : 2022 Article en page(s) : pp 35 - 60 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] auscultation d'ouvrage [Termes IGN] chaîne de traitement [Termes IGN] étalonnage d'instrument [Termes IGN] fond marin [Termes IGN] image sous-marine [Termes IGN] modélisation 3D [Termes IGN] Pacifique nord [Termes IGN] récif corallien [Termes IGN] semis de points [Termes IGN] semis de points clairsemés [Termes IGN] structure-from-motion Résumé : (auteur) Structure from motion (SfM) is an accessible and non-intrusive method of three-dimensional (3D) data capture popular for tropical coral reef surveying. In the north-east Pacific Ocean, where there are many environmentally sensitive benthic organisms whose morphology and function are equally important, SfM surveys are less commonly studied. Temperate waters pose unique challenges to SfM workflows, which must be systematically unpacked to understand their impact on data quality and veracity. This uncertainty raises broader questions concerning SfM as a spatial data-acquisition and ecological characterisation method in temperate waters, and whether a systematic workflow assessment reveals vital relationships between SfM implementation parameters, 3D data products and their implications for underwater SfM surveys. This paper, the second of two empirical assessments, reports on a series of wet-lab and dryland tests quantifying the impact that temperate waters, underwater cameras, and photograph quantity and configuration have on SfM accuracy. These tests provided crucial accuracy benchmarks informing subsequent field-based surveys and revealed that underwater SfM workflows can generate highly accurate 3D models in temperate waters. Numéro de notice : A2022-253 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : doi.org/10.1111/phor.12399 Date de publication en ligne : 07/03/2022 En ligne : https://doi.org/10.1111/phor.12399 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100216 [article]

Détection des micro et macroplastiques à partir de mesures spectrales / Martin Cubaud (2022)   

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A hybrid data model for dynamic GIS: application to marine geomorphological dynamics / Younes Hamdani in International journal of geographical information science IJGIS, vol 35 n° 8 (August 2021)  

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Applying planetary mapping methods to submarine environments: onshore-offshore geomorphology of Christiana-Santorini-Kolumbo Volcanic Group, Greece / Alexandra E. Huff in Journal of maps, vol 17 n° 3 (July 2021)  

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Evaluating the suitability of multi-scale terrain attribute calculation approaches for seabed mapping applications / Benjamin Misiuk in Marine geodesy, vol 44 n° 4 (July 2021)  

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Coral habitat mapping: a comparison between maximum likelihood, Bayesian and Dempster–Shafer classifiers / Mohammad Shawkat Hossain in Geocarto international, vol 36 n° 11 ([15/06/2021])  

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Cloud-native seascape mapping of Mozambique’s Quirimbas National Park with Sentinel-2 / Dimitris Poursanidis in Remote sensing in ecology and conservation, vol 7 n° 2 (June 2021)  

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Comparison and evaluation of high-resolution marine gravity recovery via sea surface heights or sea surface slopes / Shengjun Zhang in Journal of geodesy, vol 95 n° 6 (June 2021)  

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Mapping and quantification of the dwarf eelgrass Zostera noltii using a random forest algorithm on a SPOT 7 satellite image / Salma Benmokhtar in ISPRS International journal of geo-information, vol 10 n° 5 (May 2021)  

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Study on offshore seabed sediment classification based on particle size parameters using XGBoost algorithm / Fengfan Wang in Computers & geosciences, vol 149 (April 2021)  

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Underwater object detection and reconstruction based on active single-pixel imaging and super-resolution convolutional neural network / Mengdi Li in Sensors, vol 21 n° 1 (January 2021)  

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