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| Guimarães, Pedro Veras; Ardhuin, Fabrice; Bergamasco, Filippo; Leckler, Fabien; Filipot, Jean-francois; Shim, Jae-seol; Dulov, Vladimir; Benetazzo, Alvise. |
| Stereo imaging of the sea surface elevation provides unique field data to investigate the geometry and dynamics of oceanic waves. Typically, this technique allows retrieving the 4-D ocean topography (3-D space + time) at high frequency (up to 15–20 Hz) over a sea surface region of area ~104 m2. Stereo data fill the existing wide gap between sea surface elevation time-measurements, like the local observation provided by wave-buoys, and large-scale ocean observations by satellites. The analysis of stereo images provides a direct measurement of the wavefield without the need of any linear-wave theory assumption, so it is particularly interesting to investigate the nonlinearities of the surface, wave-current interaction, rogue waves, wave breaking, air-sea... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00631/74285/73895.pdf |
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| Veras Guimaraes, Pedro; Ardhuin, Fabrice; Sutherland, Peter; Accensi, Mickael; Hamon, Michel; Perignon, Yves; Thomson, Jim; Benetazzo, Alvise; Ferrant, Pierre. |
| Global navigation satellite systems (GNSSs) and modern motion-sensor packages allow the measurement of ocean surface waves with low-cost drifters. Drifting along or across current gradients provides unique measurements of wave–current interactions. In this study, we investigate the response of several combinations of GNSS receiver, motion-sensor package and hull design in order to define a prototype “surface kinematics buoy” (SKIB) that is particularly optimized for measuring wave–current interactions, including relatively short wave components that are important for air–sea interactions and remote-sensing applications. The comparison with existing Datawell Directional Waverider and Surface Wave Instrument Float with Tracking (SWIFT) buoys, as well as... |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00470/58136/60605.pdf |
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| Leckler, Fabien; Ardhuin, Fabrice; Peureux, Charles; Benetazzo, Alvise; Bergamasco, Filippo; Dulov, Vladimir. |
| The energy level and its directional distribution are key observations for understanding the energy balance in the wind-wave spectrum between wind-wave generation, nonlinear interactions, and dissipation. Here, properties of gravity waves are investigated from a fixed platform in the Black Sea, equipped with a stereo video system that resolves waves with frequency f up to 1.4 Hz and wavelengths from 0.6 to 11 m. One representative record is analyzed, corresponding to young wind waves with a peak frequency fp = 0.33 Hz and a wind speed of 13 m s−1. These measurements allow for a separation of the linear waves from the bound second-order harmonics. These harmonics are negligible for frequencies f up to 3 times fp but account for most of the energy at higher... |
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Palavras-chave: Circulation; Dynamics; Waves; Oceanic; Observational techniques and algorithms; Remote sensing. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00284/39524/38017.pdf |
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| Ardhuin, Fabrice; Aksenov, Yevgueny; Benetazzo, Alvise; Bertino, Laurent; Brandt, Peter; Caubet, Eric; Chapron, Bertrand; Collard, Fabrice; Cravatte, Sophie; Delouis, Jean Marc; Dias, Frederic; Dibarboure, Gerald; Gaultier, Lucile; Johannessen, Johnny; Korosov, Anton; Manucharyan, Georgy; Menemenlis, Dimitris; Menendez, Melisa; Monnier, Goulven; Mouche, Alexis; Nouguier, Frederic; Nurser, George; Rampal, Pierre; Reniers, Ad; Rodriguez, Ernesto; Stopa, Justin; Tison, Celine; Ubelmann, Clement; Van Sebille, Erik; Xie, Jiping. |
| We propose a satellite mission that uses a near-nadir Ka-band Doppler radar to measure surface currents, ice drift and ocean waves at spatial scales of 40 km and more, with snapshots at least every day for latitudes 75 to 82 degrees, and every few days for other latitudes. The use of incidence angles of 6 and 12 degrees allows for measurement of the directional wave spectrum, which yields accurate corrections of the wave-induced bias in the current measurements. The instrument's design, an algorithm for current vector retrieval and the expected mission performance are presented here. The instrument proposed can reveal features of tropical ocean and marginal ice zone (MIZ) dynamics that are inaccessible to other measurement systems, and providing global... |
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| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00442/55318/56843.pdf |
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| Peureux, Charles; Benetazzo, Alvise; Ardhuin, Fabrice. |
| The directional distribution of the energy of young waves is bimodal for frequencies above twice the peak frequency, and that distribution can be obscured by the presence of bound waves. Here we analyze in detail a typical case measured with a peak frequency fp = 0.18 Hz and a wind speed of 10.7 m s−1. The directional distribution for a given wavenumber is nearly symmetric, with the separation of two peaks of the directional distribution growing with frequency, reaching a separation of 150° at 35 times the peak wave number kp, with a separation that increases for wavenumbers up to 45 kp. When considering only free waves, the lobe ratio of peak energy density to the minimum energy level, in the wind direction, increases linearly with the non-dimensional... |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00416/52778/53657.pdf |
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| Benetazzo, Alvise; Ardhuin, Fabrice; Bergamasco, Filippo; Cavaleri, Luigi; Guimaraes, Pedro Veras; Schwendeman, Michael; Sclavo, Mauro; Thomson, Jim; Torsello, Andrea. |
| We consider the observation and analysis of oceanic rogue waves collected within spatio-temporal (ST) records of 3D wave fields. This class of records, allowing a sea surface region to be retrieved, is appropriate for the observation of rogue waves, which come up as a random phenomenon that can occur at any time and location of the sea surface. To verify this aspect, we used three stereo wave imaging systems to gather ST records of the sea surface elevation, which were collected in different sea conditions. The wave with the ST maximum elevation (happening to be larger than the rogue threshold 1.25Hs) was then isolated within each record, along with its temporal profile. The rogue waves show similar profiles, in agreement with the theory of extreme wave... |
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| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00398/50947/51718.pdf |
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| Benetazzo, Alvise; Serafino, Francesco; Bergamasco, Filippo; Ludeno, Giovanni; Ardhuin, Fabrice; Sutherland, Peter; Sclavo, Mauro; Barbariol, Francesco. |
| The use of spatial and spatio-temporal data is rapidly changing the paradigm of wind wave observations, which have been traditionally restricted to time series from single-point measurements (e.g. from buoys, wave gauges). Active and passive 2D remote sensors mounted on platforms, ships, airplanes and satellites are now becoming standards in the oceanographic community and industry. Given the covered area ranging from centimeters to kilometers, such sensors are now a valuable tool for ocean and coastal observations. In this paper, we intercompare spatio-temporal wind wave data acquired with two state-of-the-art techniques, namely the stereo wave imaging and the X-band marine radar. The comparison was performed by operating the two instruments on an... |
| Tipo: Text |
Palavras-chave: Directional wave observations; Stereo wave imaging; X-band marine radar; Modulation Transfer Function (MTF); Sea technology. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00428/53934/55108.pdf |
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