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| Aouf, L; Hauser, D; Chapron, Bertrand; Toffoli, A; Tourrain, C; Peureux, Charles. |
| In spite of continuous improvements of ocean wave models in the last decades, large errors still remain in particular under strongly forced conditions, often encountered in the Southern Ocean, where strong westerly winds generate some of the fiercest waves on Earth in almost unlimited fetch conditions. The newly launched China‐France Oceanography SATellite (CFOSAT) provides directional spectra of ocean waves for both wind seas and swells. Compared to Synthetic Aperture Radar (SAR), it can resolve shorter wavelengths in all directions, which dominate in non‐fully developed wind waves. Here, the assimilation of these CFOSAT wave number components is proved to bring more accurate predictions of wave growth compared to the assimilation of significant wave... |
| Tipo: Text |
Palavras-chave: Assimilation; Directional; Southern Ocean; SWH; Wave age; Wave number. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00668/77996/83370.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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| Flamant, C; Pelon, J; Hauser, D; Quentin, C; Drennan, Wm; Gohin, Francis; Chapron, Bertrand; Gourrion, Jerome. |
| [1] Acombination of surface wind speed (SWS) and sea state variables, derived from quasi-simultaneous airborne lidar and radar measurements, made in the framework of the Flux, Etat de mer et Teledetection en Condition de fetcH variable (FETCH) experiment, is used to analyze the evolution of surface roughness length, neutral drag coefficient, and friction velocity coefficient with fetch in the first hundred kilometers offshore over the Gulf of Lion, Western Mediterranean. The study focuses on the Tramontane/ Mistral event documented in the afternoon of 24 March 1998. Particular attention is given to SWS derived from nadir lidar measurements. The SWS retrieval methodology developed and validated for open ocean conditions by Flamant et al. [1998] has been... |
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| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/00000/10174/9582.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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| Mouche, Alexis; Chapron, Bertrand; Reul, Nicolas; Hauser, D; Quilfen, Yves. |
| [1] Asymptotic models ( small perturbation and small slope approximation at first-order, Kirchhoff approximation or two-scale model) used to predict the normalized radar cross section of the sea surface generally fail to reproduce in detail backscatter radar measurements. In particular, the predicted polarization ratio versus incidence and azimuth angles is not in agreement with experimental data. This denotes the inability of these standard models to fully take into account the roughness properties with respect to the sensor's configuration of measurement ( frequency, incidence, and polarization). On the basis of particular assumptions, to decompose the scattered electromagnetic field between zones covered with freely propagating waves and others where... |
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| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3577.pdf |
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| Ardhuin, Fabrice; Jenkins, A; Hauser, D; Reniers, A; Chapron, Bertrand. |
| The availability of new operational services for ocean circulation modeling presents a unique opportunity to rethink the operational forecasting of ocean waves and how circulation and waves may be combined to provide a better understanding of the upper ocean and enhanced services to society. The large-scale oil spill caused by the wreck of the tanker Prestige off the Spanish coast in November 2002, and uncertainties on the fate of that pollution, illustrated the gaps in means of observations and knowledge of relevant processes. The idea of a coupled atmosphere-waves-ocean model was proposed by Klaus Hasselmann [Hasselmann, 1991], in the context of climate modeling. As waves are the "gearbox" between the atmosphere and the ocean, a detailed understanding of... |
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| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-6330.pdf |
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