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| Registros recuperados: 31 | |
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| Ardhuin, Fabrice; Chapron, Bertrand; Collard, Fabrice. |
| Global observations of ocean swell, from satellite Synthetic Aperture Radar data, are used to estimate the dissipation of swell energy for a number of storms. Swells can be very persistent with energy e-folding scales exceeding 20,000 km. For increasing swell steepness this scale shrinks systematically, down to 2800 km for the steepest observed swells, revealing a significant loss of swell energy. This value corresponds to a normalized energy decay in time beta = 4.2 x 10(-6) s(-1). Many processes may be responsible for this dissipation. The increase of dissipation rate in dissipation with swell steepness is interpreted as a laminar to turbulent transition of the boundary layer, with a threshold Reynolds number of the order of 100,000. These observations... |
| Tipo: Text |
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| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6452.pdf |
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| Ardhuin, Fabrice; Brandt, Peter; Gaultier, Lucile; Donlon, Craig; Battaglia, Alessandro; Boy, François; Casal, Tania; Chapron, Bertrand; Collard, Fabrice; Cravatte, Sophie; Delouis, Jean Marc; De Witte, Erik; Dibarboure, Gerald; Engen, Geir; Johnsen, Harald; Lique, Camille; Lopez-dekker, Paco; Maes, Christophe; Martin, Adrien; Marié, Louis; Menemenlis, Dimitris; Nouguier, Frederic; Peureux, Charles; Rampal, Pierre; Ressler, Gerhard; Rio, Marie-helene; Rommen, Bjorn; Shutler, Jamie D.; Suess, Martin; Tsamados, Michel; Ubelmann, Clement; Van Sebille, Erik; Van Den Oever, Martin; Stammer, Detlef. |
| The Sea surface KInematics Multiscale monitoring (SKIM) satellite mission is designed to explore ocean surface current and waves. This includes tropical currents, notably the poorly known patterns of divergence and their impact on the ocean heat budget, and monitoring of the emerging Arctic up to 82.5°N. SKIM will also make unprecedented direct measurements of strong currents, from boundary currents to the Antarctic circumpolar current, and their interaction with ocean waves with expected impacts on air-sea fluxes and extreme waves. For the first time, SKIM will directly measure the ocean surface current vector from space. The main instrument on SKIM is a Ka-band conically scanning, multi-beam Doppler radar altimeter/wave scatterometer that includes a... |
| Tipo: Text |
Palavras-chave: Ocean current; Tropics; Arctic; Doppler; Altimetry; Sea state; Remote sensing; Ocean waves. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00498/60964/64372.pdf |
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| Hanafin, Jennifer; Quilfen, Yves; Ardhuin, Fabrice; Sienkiewicz, Joseph; Queffeulou, Pierre; Obrebski, Mathias; Chapron, Bertrand; Reul, Nicolas; Collard, Fabrice; Corman, David; De Azevedo, Eduardo B.; Vandemark, Doug; Stutzmann, Eleonore. |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00094/20538/18197.pdf |
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| Ardhuin, Fabrice; Stopa, Justin; Chapron, Bertrand; Collard, Fabrice; Smith, Madison; Thomson, Jim; Doble, Martin; Blomquist, Byron; Persson, Ola; Collins, Clarence O., Iii; Wadhams, Peter. |
| Measurements of wave heights in marginal ice zones are limited to very few in situ data. Here we revisit the linear and quasilinear theories of Synthetic Aperture Radar imaging of waves in the particular case of waves in sea ice. Instead of only working with spectra, we have developed an iterative nonlinear algorithm to estimate phase-resolved deterministic maps of wave-induced orbital velocities, from which elevation spectra can be derived. Application of this algorithm to Sentinel 1A wave mode images in the Southern Ocean shows that it produces reasonable results for swells in all directions except when they propagate at a few degrees off the range direction. The estimate of wave parameters is expected to work best when the shortest wave components,... |
| Tipo: Text |
Palavras-chave: SAR; Sentinel-1A; Ocean waves; Sea ice. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00361/47214/47451.pdf |
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| Marié, Louis; Collard, Fabrice; Nouguier, Frederic; Pineau-guillou, Lucia; Hauser, Danièle; Boy, François; Méric, Stéphane; Sutherland, Peter; Peureux, Charles; Monnier, Goulven; Chapron, Bertrand; Martin, Adrien; Dubois, Pierre; Donlon, Craig; Casal, Tania; Ardhuin, Fabrice. |
| Surface currents are poorly known over most of the world's oceans. Satellite-borne Doppler wave and current scatterometers (DWaCSs) are among the proposed techniques to fill this observation gap. The Sea surface KInematics Multiscale (SKIM) proposal is the first satellite concept built on a DWaCS design at near-nadir angles and was demonstrated to be technically feasible as part of the European Space Agency Earth Explorer program. This article describes preliminary results from a field experiment performed in November 2018 off the French Atlantic coast, with sea states representative of the open ocean and a well-known tide-dominated current regime, as part of the detailed design and feasibility studies for SKIM. This experiment comprised airborne... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00658/77056/78354.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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| Hansen, M. W.; Johannessen, J. A.; Dagestad, K. F.; Collard, Fabrice; Chapron, Bertrand. |
| Sea surface range Doppler velocities from nearly 1200 Envisat Advanced Synthetic Aperture Radar (ASAR) acquisitions between 2007 and 2011, covering the Norwegian Sea, the North Sea, and the Skagerrak Sea, have been examined. After systematic corrections, the inflow of Atlantic Water to the Norwegian Sea, via the two branches of the Norwegian Atlantic Current, is investigated. Distinct expressions of the eastern branch, the Norwegian Atlantic Slope Current, are revealed with a speed of 20-40 cm/s and a clear manifestation of topographic steering along the 500 m isobath. The western branch, the Norwegian Atlantic Front Current, is also depicted but with lower surface velocities. Moreover, parts of the Norwegian Coastal Current are also detected with... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00056/16771/14216.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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| Mouche, Alexis; Collard, Fabrice; Chapron, Bertrand; Dagestad, Knut-frode; Guitton, Gilles; Johannessen, Johnny A.; Kerbaol, Vincent; Hansen, Morten Wergeland. |
| The synthetic aperture radar (SAR) Doppler centroid has been used to estimate the scatter line-of-sight radar velocity. In weak to moderate ocean surface current environment, the SAR Doppler centroid is dominated by the directionality and strength of wave-induced ocean surface displacements. In this paper, we show how this sea state signature can be used to improve surface wind retrieval from SAR. Doppler shifts of C-band radar return signals from the ocean are thoroughly investigated by colocating wind measurements from the ASCAT scatterometer with Doppler centroid anomalies retrieved from Envisat ASAR. An empirical geophysical model function (CDOP) is derived, predicting Doppler shifts at both VV and HH polarization as function of wind speed, radar... |
| Tipo: Text |
Palavras-chave: Doppler; Surface wind; Synthetic aperture radar (SAR). |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00088/19896/17554.pdf |
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| Husson, R.; Ardhuin, Fabrice; Collard, Fabrice; Chapron, Bertrand; Balanche, Abel. |
| Swells radiating across ocean basins are fingerprints of the large ocean storms that generated them, which are otherwise poorly observed. Here we analyze the signature of one swell event in the seismic noise recorded all around the Pacific and we show that it is a natural complement to the global coverage provided by the Synthetic Aperture Radar wave mode data from ENVISAT. In particular the seismic stations are much more sensitive to low frequency and amplitude signals than buoys and SAR, capturing swell forerunners a couple of days before they can be detected from space or in situ data. This information helps detect in the SAR measurements the presence of very long swell, with periods of 22 s in our case example, that were otherwise excluded. Citation:... |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00092/20328/17977.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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| Rouault, M. J.; Mouche, Alexis; Collard, Fabrice; Johannessen, J. A.; Chapron, Bertrand. |
| Over 2 years of surface current information collected in the Agulhas Current region and derived from the Doppler centroid anomalies of Envisat's advanced synthetic aperture radar (ASAR) are examined. The sources of errors and potential use of ASAR surface current velocities for oceanographic research are assessed. ASAR surface current velocities are compared to surface drifter data and merged altimetry observations. Maps of sea surface temperature are used to establish the ASAR's capacity to capture the synoptic circulation. Discrepancies between observed and predicted ASAR velocities result predominantly from inadequate wind corrections combined with radar incidence angles below 30 degrees. Occasionally observed wind-induced outliers cause a bias in the... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00016/12712/9639.pdf |
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| Ardhuin, Fabrice; Stopa, Justin; Chapron, Bertrand; Collard, Fabrice; Husson, Romain; Jensen, Robert E.; Johannessen, Johnny; Mouche, Alexis; Passaro, Marcello; Quartly, Graham D.; Swail, Val; Young, Ian. |
| Sea state information is needed for many applications, ranging from safety at sea and on the coast, for which real time data are essential, to planning and design needs for infrastructure that require long time series. The definition of the wave climate and its possible evolution requires high resolution data, and knowledge on possible drift in the observing system. Sea state is also an important climate variable that enters in air-sea fluxes parameterizations. Finally, sea state patterns can reveal the intensity of storms and associated climate patterns at large scales, and the intensity of currents at small scales. A synthesis of user requirements leads to requests for spatial resolution at kilometer scales, and estimations of trends of a few centimeters... |
| Tipo: Text |
Palavras-chave: Sea state; Waves; Altimeter; SAR; Swell; Remote sensing; Buoy; Microseisms. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00489/60090/63432.pdf |
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| Stopa, Justin; Ardhuin, Fabrice; Husson, Romain; Jiang, Haoyu; Chapron, Bertrand; Collard, Fabrice. |
| Swells are found in all oceans and strongly influence the wave climate and air-sea processes. The poorly known swell dissipation is the largest source of error in wave forecasts and hindcasts. We use synthetic aperture radar data to identify swell sources and trajectories, allowing a statistically significant estimation of swell dissipation. We mined the entire Envisat mission 2003–2012 to find suitable storms with swells (13 < T < 18 s) that are observed several times along their propagation. This database of swell events provides a comprehensive view of swell extending previous efforts. The analysis reveals that swell dissipation weakly correlates with the wave steepness, wind speed, orbital wave velocity, and the relative direction of wind and... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00324/43534/43079.pdf |
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| Registros recuperados: 31 | |
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