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| Johannessen, Ja; Chapron, Bertrand; Collard, F; Rio, Mh; Piolle, Jean-francois; Gaultier, Lucile; Quartly, G; Shutler, J; Escola, R; Raj, Rp; Donlon, C; Danielson, R; Korosov, Anton; Nencioli, F; Roca, M; Hansen, M. |
| Tipo: Text |
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| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00450/56152/57695.pdf |
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| Ardhuin, Fanny; Mercier, G; Collard, F; Garello, R. |
| A methodology is proposed for the semiautomatic detection, characterization, and classification of slicks detected in C-band Synthetic Aperture Radar (SAR). For the first detection step, automatic algorithms were tested on Environmental Research Satellite (ERS) and Environmental Satellite (EnviSat) images acquired during the Prestige tanker accident. These tests reveal that simple filter or segmentation methods efficiently detect slicks with high contrasts and simple shapes, while a new and more complex multiscale method is able to detect a wider range of slicks. The characteristics of automatically detected slicks are then combined with meteooceanic data in order to eliminate slicks related to wind anomalies and current fronts. The data suggest that... |
| Tipo: Text |
Palavras-chave: Synthetic aperture radar SAR; Satellite measurement; Oil pollution; Image analysis. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-1132.pdf |
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| Johannessen, J; Chapron, Bertrand; Collard, F; Kudryavtsev, V; Mouche, Alexis; Akimov, D; Dagestad, K. |
| Previous analysis of Advanced Synthetic Aperture Radar (ASAR) signals collected by ESA's Envisat has demonstrated a very valuable source of high-resolution information, namely, the line-of-sight velocity of the moving ocean surface. This velocity is estimated from a Doppler frequency shift, consistently extracted within the ASAR scenes. The Doppler shift results from the combined action of near surface wind on shorter waves, longer wave motion, wave breaking and surface current. Both kinematic and dynamic properties of the moving ocean surface roughness can therefore be derived from the ASAR observations. The observations are compared to simulations using a radar imaging model extended to include a Doppler shift module. The results are promising.... |
| Tipo: Text |
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| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-5168.pdf |
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| Mouche, Alexis; Chapron, Bertrand; Reul, Nicolas; Collard, F. |
| Sea surface motions can produce different measured Doppler shifts with respect to instrumental configurations (incidence angle, electromagnetic wavelength, polarization). Under Gaussian statistics for the sea surface elevation and in the general framework of asymptotic theories for ocean surface electromagnetic wave scattering, Doppler shifts can be predicted. The small-slope, Kirchhoff, local curvature and resonant curvature approximations are compared in the backscatter configuration. Predicted Doppler shifts for Kirchhoff and small-slope approximations in co-polarized configuration are insensitive to the polarization state. On the other hand, the local and resonant curvature solutions, through a phase perturbation formalism, yield to significant... |
| Tipo: Text |
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| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-3576.pdf |
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