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Relating statistical characteristics of cross-polarized phase difference to speckle noise / Huimin Li in Journal of applied remote sensing, vol 9 (2015)  

Public [article]  inJournal of applied remote sensing > vol 9 (2015) . - 8 p. Titre : Relating statistical characteristics of cross-polarized phase difference to speckle noise Type de document : Article/Communication Auteurs : Huimin Li, Auteur ; Yunhua Wang, Auteur Année de publication : 2015 Article en page(s) : 8 p. Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] données polarimétriques [Termes IGN] filtrage du bruit [Termes IGN] image radar moirée [Termes IGN] matrice de covariance [Termes IGN] phase [Termes IGN] polarimétrie radar [Termes IGN] polarisation croisée Résumé : (auteur) A qualitative relationship between the statistical behavior of cross-polarized phase difference ϕhvvh and dominant noise type is examined based on the polarimetric noise model proposed. The noise model focusing on the covariance matrix is able to separate the multiplicative noise which only affects the amplitude from the additive noise that alters both the amplitude and phase. In the case of low noise, the phase is not affected by the noise and ϕhvvh distribution is predicted to be centered at 0 deg in terms of reciprocity theorem. The case of strong noise is much more complicated as the dominant noise type plays an important role in the statistics of ϕhvvh. The phase over the area where multiplicative noise dominates is not altered, thus the ϕhvvh distribution is expected to have similar behaviors to the case of low noise. However, the dominant additive noise would significantly affect the phase so that an obvious deviation from 0 deg for ϕhvvh distribution is expected. Experiments with Radarsat-2 full polarimetric imageries further validate this qualitative relationship. Numéro de notice : A2015-101 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1117/1.JRS.9.090599 En ligne : http://remotesensing.spiedigitallibrary.org/article.aspx?articleid=2091528 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75392 [article]

Effects of atmospheric stability and wind fetch on microwave sea echoes / Yunhua Wang in IEEE Transactions on geoscience and remote sensing, vol 52 n° 2 (February 2014)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 52 n° 2 (February 2014) . - pp 929 - 935 Titre : Effects of atmospheric stability and wind fetch on microwave sea echoes Type de document : Article/Communication Auteurs : Yunhua Wang, Auteur ; Yanmin Zhang, Auteur ; Haihu Chen, Auteur ; Lixin Guo, Auteur Année de publication : 2014 Article en page(s) : pp 929 - 935 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] écho radar [Termes IGN] stabilité [Termes IGN] surface de la mer [Termes IGN] vent Résumé : (Auteur) The influences of atmospheric stability and wind fetch on microwave scattering from sea surfaces are presented. The equivalent neutral wind speed (ENWS) and the friction velocity (FV) above sea surface are evaluated by the similarity theory of Monin and Obukhov in combination with the Charnock relation. The numerical simulations show that atmospheric stability and wind fetch would make effects on ENWS and, therefore, further on the scattering coefficients (NRCS). And the NRCS decreases with increasing air-sea temperature difference (ÄT=Ta-Ts) because the ENWS is lower than actual wind speed in stable atmospheric condition, and vice versa. Moreover, the ENWS/FV and the NRCS decrease with increasing wind fetch under unstable atmospheric condition. However, in stable atmospheres, the ENWS/FV and the NRCS are almost insensitive to wind fetch. In this paper, the response of NRCS to ÄT is also discussed. Compared with FV, the variations of the angle spread function with ÄT can be neglected because of its minor contribution. Numéro de notice : A2014-071 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2013.2245673 En ligne : https://doi.org/10.1109/TGRS.2013.2245673 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32976 [article]

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