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Discrimination of different sea ice types from CryoSat-2 satellite data using an Object-based Random Forest (ORF) / Su Shu in Marine geodesy, Vol 43 n° 3 (May 2020)  

Public [article]  inMarine geodesy > Vol 43 n° 3 (May 2020) . - pp 213 - 233 Titre : Discrimination of different sea ice types from CryoSat-2 satellite data using an Object-based Random Forest (ORF) Type de document : Article/Communication Auteurs : Su Shu, Auteur ; Xinghua Zhou, Auteur ; Zhanchi Liu, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : pp 213 - 233 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] Arctique, océan [Termes IGN] classification orientée objet [Termes IGN] classification par forêts d'arbres décisionnels [Termes IGN] forme d'onde [Termes IGN] glace de mer [Termes IGN] image Cryosat Résumé : (Auteur) Sea ice type is one of the most sensitive variables in Arctic sea ice monitoring, and it is important for the retrieval of ice thickness. In this study, we analyzed various waveform features that characterize the echo waveform shape and Sigma0 (i.e., backscatter coefficient) of CryoSat-2 synthetic aperture radar altimeter data over different sea ice types. Arctic and Antarctic Research Institute operational ice charts were input as reference. An object-based random forest (ORF) classification method is proposed with overall classification accuracy of 90.1%. Accuracy of 92.7% was achieved for first-year ice (FYI), which is the domain ice type in the Arctic. Accuracy of 76.7% was achieved at the border of FYI and multiyear ice (MYI), which is better than current state-of-the-art methods. Accuracy of 83.8% was achieved for MYI. Results showed the overall accuracy of the ORF method was increased by ∼8% in comparison with other methods, and the classification accuracy at the border of FYI and MYI was increased by ∼10.5%. Nevertheless, ORF classification performance might be influenced by the selected waveform features, snow loading, and the ability to distinguish sea ice from leads. Numéro de notice : A2020-183 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01490419.2019.1671560 Date de publication en ligne : 21/10/2019 En ligne : https://doi.org/10.1080/01490419.2019.1671560 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94971 [article]

Seasonal Deformation of Permafrost in Wudaoliang Basin in Qinghai-Tibet Plateau Revealed by StaMPS-InSAR / Ping Lu in Marine geodesy, Vol 43 n° 3 (May 2020)  

Public [article]  inMarine geodesy > Vol 43 n° 3 (May 2020) . - pp 248 - 268 Titre : Seasonal Deformation of Permafrost in Wudaoliang Basin in Qinghai-Tibet Plateau Revealed by StaMPS-InSAR Type de document : Article/Communication Auteurs : Ping Lu, Auteur ; Jiangping Han, Auteur ; Tong Hao, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : pp 248 - 268 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] climat froid [Termes IGN] image Sentinel-SAR [Termes IGN] Tibet Résumé : (Auteur) Permafrost is extremely sensitive to variance in external hydrothermal conditions. InSAR has advantages in monitoring surface deformation with decent temporal and spatial resolution as well as millimeter precision. In particular, the StaMPS-InSAR method can remove the disturbances of inaccurate digital elevation model (DEM), atmospheric delays and spatiotemporal decorrelation for an accurate estimation of temporal surface deformation. In this paper, a set of ascending and descending Sentinel-1 imageries spanning from March 2017 to June 2018 were acquired and processed by StaMPS-InSAR in order to investigate dynamic changes of permafrost in Wudaoliang Basin, Qinghai-Tibet Plateau (QTP). The results revealed that significant seasonal changes of permafrost, namely subsidence (thawing) in summer and uplift (freezing) in winter, can be observed throughout the Wudaoliang region. This study shows the StaMPS-InSAR analysis on Sentinel-1 datasets has great potential in regional permafrost investigation. Numéro de notice : A2020-184 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01490419.2019.1698480 Date de publication en ligne : 10/12/2019 En ligne : https://doi.org/10.1080/01490419.2019.1698480 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94974 [article]

Improved arctic ocean mass variability inferred from time-variable gravity with constraints and dual leakage correction / Dapeng Mu in Marine geodesy, Vol 43 n° 3 (May 2020)  

Public [article]  inMarine geodesy > Vol 43 n° 3 (May 2020) . - pp 269 - 284 Titre : Improved arctic ocean mass variability inferred from time-variable gravity with constraints and dual leakage correction Type de document : Article/Communication Auteurs : Dapeng Mu, Auteur ; Tianhe Xu, Auteur ; Guochang Xu, Auteur Année de publication : 2020 Article en page(s) : pp 269 - 284 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] Arctique, océan [Termes IGN] données GRACE [Termes IGN] harmonique sphérique [Termes IGN] marée océanique Résumé : (Auteur) The ocean mass variability inferred from Gravity Recovery and Climate Experiment (GRACE) satellites mission is challenged by the stripes and the leakage across land-ocean boundary. The recently released GRACE mascons solutions are advanced by applying constraints that remove efficiently the stripes and dual leakage correction that restores the coastal ocean mass variability. Here we quantitatively evaluate the improvement in the Arctic Ocean mass variability by GRACE mascons. To do so, we compare the combination of GRACE solutions (including the mascons solutions and traditional spherical harmonic coefficients (SHCs) solutions) and the steric estimates against the altimeter observations. Our results suggest that mascons solutions produce stronger correlations compared to SHCs solutions, especially along the coastal zone, indicating the importance of the dual leakage correction. Stronger correlation is produced by the mascons over a small basin in the interior of the Arctic Ocean, suggesting that mascons solutions deliver better ocean mass variability than the SHCs solutions. Since the comparisons are carried out over two sub-basins, we conclude that mascons are able to provide better regional ocean mass variability that may have implications for regional sea level budget, in particular over the coastal zone. Numéro de notice : A2020-185 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01490419.2020.1711832 Date de publication en ligne : 17/01/2020 En ligne : https://doi.org/10.1080/01490419.2020.1711832 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94975 [article]