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Registros recuperados: 5
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A model of sea-foam thickness distribution for passive microwave remote sensing applications ArchiMer
Reul, Nicolas; Chapron, Bertrand.
[1] Foam formations at the sea surface significantly contribute to microwave brightness temperature signatures over the ocean for moderate to high wind speeds. The thickness of foam layers generated by breaking waves follows a specific distribution due to unsteadiness of breaking and the large range of wave scales involved in the phenomenon. Although the effect of a distributed thickness-parameter on the foam-induced microwave brightness temperature may be comparable to or larger than the fractional whitecap coverage, it is not yet included in brightness models. To fill this gap, we develop a dynamical model for the conditional fraction of sea-surface covered by whitecaps with given thickness, as a function of wind speed. It is an integrated function of...
Tipo: Text Palavras-chave: Sea foam; Breaking waves; Thickness; Fractional coverage; Microwave brightness temperature.
Ano: 2003 URL: http://archimer.ifremer.fr/doc/00000/10693/9320.pdf
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Modélisation de l'évolution du trait de côte et de la protection du littoral dans le golfe de Tunis OceanDocs
Ben Mouelli, I.; Bejaoui, B.; Raïs, S.; Brahim, M..
Ce travail s’intéresse à l’étude de l’évolution et de la protection du littoral de la banlieue Nord de Tunis par modélisation à l’aide du code UNIBEST. Pour ce faire, une étude bibliographique a été élaborée concernant la morphologie des côtes, les facteurs naturels (houle, marée) l’influençant ainsi que les différents ouvrages de protection utilisés. L’étude du littoral de la banlieue Nord de Tunis a nécessité la subdivision de la région en zones d’étude afin de valider les hypothèses de base du modèle UNIBEST. La procédure de calage est effectuée seulement sur une zone. La modélisation de l’évolution du littoral de la banlieue Nord de Tunis a montré l’existence de deux sites menacés par l’érosion : Le premier site correspond à la côte de Gammarth entre...
Tipo: Journal Contribution Palavras-chave: Breaking waves; Breakwaters; Refraction; Mathematical models; Swell; Diffraction.
Ano: 2002 URL: http://hdl.handle.net/1834/242
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On C-Band Quad-Polarized Synthetic Aperture Radar Properties of Ocean Surface Currents ArchiMer
Fan, Shengren; Kudryavtsev, Vladimir; Zhang, Biao; Perrie, William; Chapron, Bertrand; Mouche, Alexis.
We present new results for ocean surface current signatures in dual co- and cross-polarized synthetic aperture radar (SAR) images. C-band RADARSAT-2 quad-polarized SAR ocean scenes are decomposed into resonant Bragg scattering from regular (non-breaking) surface waves and scattering from breaking waves. Surface current signatures in dual co- and cross-polarized SAR images are confirmed to be governed by the modulations due to wave breaking. Due to their small relaxation scale, short Bragg waves are almost insensitive to surface currents. Remarkably, the contrast in sensitivity of the non-polarized contribution to dual co-polarized signals is found to largely exceed, by a factor of about 3, the contrast in sensitivity of the corresponding cross-polarized...
Tipo: Text Palavras-chave: Quad-polarized SAR; Ocean surface current; Polarization decomposition; Bragg scattering; Breaking waves.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00588/70030/67948.pdf
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On radar imaging of current features: 1. Model and comparison with observations - art. no. C07016 ArchiMer
Kudryavtsev, V; Akimov, D; Johannessen, Johnny; Chapron, Bertrand.
[1] A new radar imaging model of ocean current features is proposed. The simulated normalized radar cross section ( NRCS) takes into account scattering from "regular'' surfaces ( by means of resonant Bragg scattering and specular reflections) and scattering from breaking waves. The description of background wind waves and their transformation in nonuniform medium is based on solution of the wave action conservation equation. Wave breaking plays a key role in the radar imaging model. Breaking waves scatter radio waves ( thus directly contributing to the NRCS), provide energy dissipation in wind waves ( thus defining the wave spectrum of intermediate scale waves), and generate short surface waves ( thus affecting Bragg scattering). Surface current,...
Tipo: Text Palavras-chave: Breaking waves; Scattering; Radar imaging model; Ocean surface current.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/publication-762.pdf
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The spectral wave model, WAM, adapted for applications with high spatial resolution OMA
Monbaliu, J.; Padilla-Hernandez, R.; Hargreaves, J.C.; Carretero Albiach, J.C.; Luo, W.; Sclavo, M.; Günther, H..
New features have been added and several necessary changes have been made to the standard WAM-cycle4 (WAMC4) model code for it to run efficiently when applied to shallow water regions. The restriction of having a source term integration time step smaller than or equal to the propagation time step was relaxed, considerably reducing the computational time needed. An additional reduction in computing time and an increase in accuracy were obtained by introducing a split-frequency time step. There is now a choice of using the octant or quadrant coordinate system for the propagation of the wave energy. The source term integration and, more particularly, the use of a limiter on the energy growth, were studied. For the evaluation of the energy decay in shallow...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Breaking waves; Coastal engineering; Mathematical models; Shallow water; Wave predicting; Wave propagation.
Ano: 2000 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=6924
Registros recuperados: 5
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