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| Registros recuperados: 11 | |
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| Yurovskaya, Maria; Kudryavtsev, Vladimir; Chapron, Bertrand; Collard, Fabrice. |
| The Sentinel-2 MultiSpectral Instrument (MSI) collects multiple spectral band images, corresponding to specific sensing wavelengths and spatial resolutions, i.e. 10 m, 20 m and 60 m, respectively. Images are collected one at the time with a given time-lag between observations. Under favorable conditions, spatio-temporal characteristics of propagating ocean surface waves can thus uniquely be retrieved. A method for surface current vector field reconstruction is then developed. Demonstrated over different deep ocean regions, the retrieved surface current fields well compare with medium-resolution ocean circulation model or derived-velocities from altimeter measurements. At finer scales, the surface wave-conservation law is recovered, with the associated... |
| Tipo: Text |
Palavras-chave: Ocean currents; Sea surface optical images; Wave dispersion relation; Time lag; Wave breaking; Sentinel-2; Satellite methods. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00587/69865/67918.pdf |
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| Hwang, Paul A.; Reul, Nicolas; Meissner, Thomas; Yueh, Simon H.. |
| Whitecaps manifest surface wave breaking that impacts many ocean processes, of which surface wind stress is the driving force. For close to a half century of quantitative whitecap reporting, only a small number of observations are obtained under conditions with wind speed exceeding 25 m/s. Whitecap contribution is a critical component of ocean surface microwave thermal emission. In the forward solution of microwave thermal emission, the input forcing parameter is wind speed, which is used to generate the modeled surface wind stress, surface wave spectrum, and whitecap coverage necessary for the subsequent electromagnetic (EM) computation. In this respect, microwave radiometer data can be used to evaluate various formulations of the drag coefficient,... |
| Tipo: Text |
Palavras-chave: Wave breaking; Wind stress; Wind waves; Severe storms; Microwave observations; Satellite observations. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00506/61757/65730.pdf |
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| Pivaev, P. D.; Kudryavtsev, V. N.; Balashova, E. A.; Chapron, Bertrand. |
| Purpose. The aim of the article is to study manifestations of the underwater topography features in the northern part of the White Sea in the images made by the spaceborn synthetic aperture radars (SAR) Sentinel-1A, Sentinel-1B. Methods and Results. In the SAR images, the bottom features are revealed as bright and dark brightness anomalies. The anomalies were observed at the wind speed ranging from 2.6 to 10.8 m/s, and became reverse (bright anomalies turned dark and vice versa), when a tidal current changed its direction. It is shown that the observed SAR imagery contrasts correlate to divergence of a current formed by interaction of a tidal flow with the bottom topography inhomogeneities. The simulated SAR contrasts agree with the observations, and... |
| Tipo: Text |
Palavras-chave: Bottom topography; Sentinel-1; SAR; Wave breaking; Current divergence. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00648/75989/76890.pdf |
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| Leckler, Fabien; Ardhuin, Fabrice; Filipot, Jean-francois; Mironov, Alexey. |
| Whitecaps are the main sink of wave energy and their occurrence has been related to the steepness of the waves. Recent parameterizations of the wave dissipation in numerical models are based on this property, but wave models have seldom been verified in terms of whitecap properties. Here we analyze and adjust the breaking statistics used in two recent wave dissipation parameterizations implemented in the spectral wave model WAVEWATCH III (R) and now used operationaly at NOAA/NCEP. For dominant breaking waves, the reduction of breaking probabilities with wave age is well reproduced. Across the spectrum, the parameterizations produce a reasonable distribution of breaking fronts for wave frequencies up to three times the dominant frequency, but fail to... |
| Tipo: Text |
Palavras-chave: Wave breaking; Dissipation source term; Whitecap statistics. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00155/26579/26386.pdf |
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| Mouche, Alexis; Hauser, D; Kudryavtsev, V. |
| [1] An analysis of radar observations in C band combined with models is proposed to study some of the ocean surface properties and their relation with the sea surface backscatter. The electromagnetic part of the models is of different kinds: composite Bragg model with or without including effect of wave breaking zones on the normalized radar cross-section (NRCS), geometrical optics approximation and small-slope approximation model. The surface description is based on the wave spectrum proposed by Kudryavtsev et al. (2003), but tests with the spectrum of Elfouhaily et al. (1997) are also discussed to assess our conclusions. The originality is to use not only the NRCS in HH and VV polarizations, but also their difference in linear units. First, we show that... |
| Tipo: Text |
Palavras-chave: Wave breaking; Sea surface anisotropy; Radar cross section. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1877.pdf |
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| Kudryavtsev, V; Hauser, D; Caudal, G; Chapron, Bertrand. |
| normalized radar cross section (NRCS) over the sea surface. However, these models are not able to correctly reproduce the NRCS in all configurations. In particular, even if they may provide consistent results for vertical transmit and receive (VV) polarization, they fail in horizontal transmit and receive (HH) polarization. In addition, there are still important discrepancies between model and observations of the radar modulation transfer function (MTF), which relates the modulations of the NRCS to the long waves. In this context, we have developed a physical model that takes into account not only the Bragg mechanism but also the non-Bragg scattering associated with radio wave scattering from breaking waves. The same model was built to explain both the... |
| Tipo: Text |
Palavras-chave: Radar cross section; Ocean surface; Surface gravity waves; Wave breaking; Modulation transfer function; Non Bragg scattering. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/00000/10183/9581.pdf |
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| Filipot, Jean-francois; Guimaraes, P.; Leckler, Fabien; Hortsmann, J.; Carrasco, R.; Leroy, Elodie; Fady, N.; Accensi, Mickael; Prevosto, Marc; Duarte, Rui; Roeber, V.; Benetazzo, A.; Raoult, C.; Franzetti, M.; Varing, Audrey; Le Dantec, N.. |
| This paper presents results from an experiment designed to improve the understanding of the relationship between extreme breaking waves and their mechanical loading on heritage offshore lighthouses. The experiment, conducted at La Jument, an iconic French offshore lighthouse, featured several records of wave, current and structure accelerations acquired during severe storm conditions, with individual waves as high as 24 m. Data analysis focuses on a storm event marked by a strong peak in the horizontal accelerations measured inside La Jument. Thanks to stereo-video wave measurements synchronized to the acceleration record we were able to identify and describe the breaking wave responsible for this intense loading. Our observations suggest that this giant... |
| Tipo: Text |
Palavras-chave: Extreme wave; Wave breaking; Wave loading. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00513/62480/66803.pdf |
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| Registros recuperados: 11 | |
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