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| Registros recuperados: 16 | |
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| 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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| Kudryavtsev, Vladimir; Golubkin, Pavel; Chapron, Bertrand. |
| An analytical model is derived to efficiently describe the wave energy distribution along the main transects of a moving extreme weather event. The model essentially builds on a generalization of the self-similar wave growth model and the assumption of a strongly dominant single spectral mode in a given quadrant of the storm. The criterion to anticipate wave enhancement with the generation of trapped abnormal waves defined as inline image, with inline image, inline image, and inline image, radial distance, average sustained wind speed, and translation velocity, respectively. Constants inline image and inline image follow the fetch-law definitions. If forced during a sufficient time scale interval, also defined from this generalized self-similar wave growth... |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00295/40644/39603.pdf |
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| Kudryavtsev, Vladimir; Yurovskaya, Maria; Chapron, Bertrand; Collard, Fabrice; Donlon, Craig. |
| Under favorable imaging conditions, the Sentinel-2 Multi-Spectral Instrument (MSI) can provide spectacular and novel quantitative ocean surface wave directional measurements in satellite Sun Glitter Imagery (SSGI). Owing to a relatively large-swath with high-spatial resolution (10 m), ocean surface roughness mapping capabilities, changes in ocean wave energy, and propagation direction can be precisely quantified at very high resolution, across spatial distances of 10 km and more. This provides unique opportunities to study ocean wave refraction induced by spatial varying surface currents. As expected and demonstrated over the Grand Agulhas current area, the mesoscale variability of near-surface currents, documented and reconstructed from satellite... |
| Tipo: Text |
Palavras-chave: Satellite Sun Glitter Imagery; Ocean surface waves; Waves transformation on the currents. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00381/49281/49677.pdf |
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| Gommenginger, Christine; Chapron, Bertrand; Hogg, Andy; Buckingham, Christian; Fox-kemper, Baylor; Eriksson, Leif; Soulat, Francois; Ubelmann, Clément; Ocampo-torres, Francisco; Nardelli, Bruno Buongiorno; Griffin, David; Lopez-dekker, Paco; Knudsen, Per; Andersen, Ole; Stenseng, Lars; Stapleton, Neil; Perrie, William; Violante-carvalho, Nelson; Schulz-stellenfleth, Johannes; Woolf, David; Isern-fontanet, Jordi; Ardhuin, Fabrice; Klein, Patrice; Mouche, Alexis; Pascual, Ananda; Capet, Xavier; Hauser, Daniele; Stoffelen, Ad; Morrow, Rosemary; Aouf, Lotfi; Breivik, Øyvind; Fu, Lee-lueng; Johannessen, Johnny A.; Aksenov, Yevgeny; Bricheno, Lucy; Hirschi, Joel; Martin, Adrien Ch; Martin, Adiran P; Nurser, George; Polton, Jeff; Wolf, Judith; Johnsen, Harald; Soloviev, Alexander; Jacobs, Gregg A.; Collard, Fabrice; Groom, Steve; Kudryavtsev, Vladimir; Wilkin, John; Navarro, Victor; Babanin, Alex; Martin, Matthew; Siddorn, John; Saulter, Andrew; Rippeth, Tom; Emery, Bill; Maximenko, Nikolai; Romeiser, Roland; Graber, Hans; Azcarate, Aida Alvera; Hughes, Chris W.; Vandemark, Doug; Silva, Jose Da; Leeuwen, Peter Jan Van; Naveira-garabato, Alberto; Gemmrich, Johannes; Mahadevan, Amala; Marquez, Jose; Munro, Yvonne; Doody, Sam; Burbidge, Geoff. |
| High-resolution satellite images of ocean color and sea surface temperature reveal an abundance of ocean fronts, vortices and filaments at scales below 10 km but measurements of ocean surface dynamics at these scales are rare. There is increasing recognition of the role played by small scale ocean processes in ocean-atmosphere coupling, upper-ocean mixing and ocean vertical transports, with advanced numerical models and in situ observations highlighting fundamental changes in dynamics when scales reach 1 km. Numerous scientific publications highlight the global impact of small oceanic scales on marine ecosystems, operational forecasts and long-term climate projections through strong ageostrophic circulations, large vertical ocean velocities and mixed layer... |
| Tipo: Text |
Palavras-chave: Satellite; Air sea interactions; Upper ocean dynamics; Submesoscale; Coastal; Marginal ice zone; Radar; Along-track interferometry. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00510/62121/66325.pdf |
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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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| Kudryavtsev, Vladimir; Myasoedov, Alexander; Chapron, Bertrand; Johannessen, Johnny A.; Collard, Fabrice. |
| A synergetic approach for quantitative analysis of high-resolution ocean synthetic aperture radar (SAR) and imaging spectrometer data, including the infrared (IR) channels, is suggested. This approach first clearly demonstrates that sea surface roughness anomalies derived from Sun glitter imagery compare very well to SAR roughness anomalies. As further revealed using these fine-resolution (similar to 1 km) observations, the derived roughness anomaly fields are spatially correlated with sharp gradients of the sea surface temperature (SST) field. To quantitatively interpret SAR and optical (in visible and IR ranges) images, equations are derived to relate the "surface roughness" signatures to the upper ocean flow characteristics. As developed, a direct link... |
| Tipo: Text |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00079/18999/16570.pdf |
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| Wergeland, Morten; Kudryavtsev, Vladimir; Chapron, Bertrand; Brekke, Camilla; Johannessen, Johnny A.. |
| Radarsat-2 C-band quad-polarization SAR observations of crude oil, emulsion, and plant oil slicks acquired in the wind speed range from 4 to 8 m/s and incidence angles from 30 degrees to 50 degrees are analyzed to yield new insights into the attenuation of short waves and breaking waves by surface slicks in real conditions. To provide a direct quantitative assessment of the surface wave damping, the measurements are decomposed into polarization difference (PD), polarization ratio (PR), nonpolarized (NP), and cross-polarized (CP) components. The PD signals relate to the extent of Bragg damping in the slick areas, over which the PR is systematically higher than over the ambient sea surface. Attenuation of the breaking waves is revealed to affect both the CP... |
| Tipo: Text |
Palavras-chave: Oil pollution; Radar imaging; Sea surface; Surface waves. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00363/47460/47484.pdf |
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| Kudryavtsev, Vladimir; Monzikova, Anna; Combot, Clement; Chapron, Bertrand; Reul, Nicolas; Quilfen, Yves. |
| Changes of sea surface temperature (SST) and height (SSH) derived from 20‐days passive microwave and altimeter measurements for three tropical cyclones (TCs), Jimena, Ignacio and Kilo, during the 2015 Pacific hurricane season, sampling different stages of intensification, wind speeds, radii, Coriolis parameter, translation velocities, and ocean stratification conditions, are reported and analyzed. As triggered along the path of moving TCs, very large interior ocean displacements can occur to leave prominent SSH anomalies in the TC wake. Resulting surface depressions can reach.3‐.5 m, depending upon size, translation speed, and ocean stratification conditions. These signatures can be quite persistent, i.e. more than few weeks, to possibly be intercepted... |
| Tipo: Text |
Palavras-chave: Tropical cyclones; Surface temperature anomalies; Surface height anomalies. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00491/60252/63653.pdf |
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| Yurovskaya, Maria; Rascle, Nicolas; Kudryavtsev, Vladimir; Chapron, Bertrand; Marie, Louis; Molemaker, Jeroen. |
| Reconstruction and evolution of two-dimensional spectra of surface waves in the Gulf of Mexico are derived from airborne sun-glitter imagery. As the proposed method is based on a linear transfer function deduced from the shape of the sunglitter brightness, the absolute wavenumber elevation spectrum does not require any additional assumption or information about sky brightness, wind or wave energy. The detailed description of the airborne image processing method is given. As demonstrated, retrieved spectra agree well with nearby NDBC buoy data, both for spectrum shape, level and energy angular distribution. The 180-degree wave direction ambiguity, inherent to image-derived spectra, is eliminated by using cross-correlation analysis between two consecutive... |
| Tipo: Text |
Palavras-chave: Sunglitter; Sea surface waves; Directional wave spectrum; Aerial photography; Field measurements; Remote sensing observations; High resolution; Drone. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00465/57712/60174.pdf |
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| Kudryavtsev, Vladimir; Chapron, Bertrand. |
| The wave generation model based on the rapid distortion concept significantly underestimates empirical values of the wave growth rate. As suggested before, inclusion of the aerodynamic roughness modulations effect on the amplitude of the slope-correlated surface pressure could potentially reconcile this model approach with observations. This study explores the role of short-scale breaking modulations to amplify the growth rate of modulating longer waves. As developed, airflow separations from modulated breaking waves result in strong modulations of the turbulent stress in the inner region of the modulating waves. In turn, this leads to amplifying the slope-correlated surface pressure anomalies. As evaluated, such a mechanism can be very efficient for... |
| Tipo: Text |
Palavras-chave: Atm; Ocean Structure; Phenomena; Atmosphere-ocean interaction. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00313/42414/41759.pdf |
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| Yurovsky, Yury; Kudryavtsev, Vladimir; Grodsky, Semyon; Chapron, Bertrand. |
| Multi-year field measurements of sea surface Ka-band dual-co-polarized (vertical transmit–receive polarization (VV) and horizontal transmit–receive polarization (HH)) radar Doppler characteristics from an oceanographic platform in the Black Sea are presented. The Doppler centroid (DC) estimated using the first moment of 5 min averaged spectrum, corrected for measured sea surface current, ranges between 0 and ≈1 m/s for incidence angles increasing from 0 to 70∘ . Besides the known wind-to-radar azimuth dependence, the DC can also depend on wind-to-dominant wave direction. For co-aligned wind and waves, a negative crosswind DC residual is found, ≈−0.1 m/s, at ≈20 ∘ incidence angle, becoming negligible at ≈ 60 ∘ , and raising to, ≈+0.5 m/s, at 70∘ . For our... |
| Tipo: Text |
Palavras-chave: Radar; Scatterometer; Ocean; Backscatter; Doppler shift; Doppler centroid; Sea surface current; Wind drift; Modulation; Transfer function; Empirical model. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00489/60077/63399.pdf |
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| Registros recuperados: 16 | |
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