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Registros recuperados: 8
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A numerical model for free infragravity waves: Definition and validation at regional and global scales ArchiMer
Ardhuin, Fabrice; Rawat, Arshad; Aucan, Jerome.
The spectral wave model WAVEWATCH III is extended from the windsea and swell band to lower frequencies, in order to represent free waves in the infragravity (IG) wave band. This extension is based on an empirical source of IG energy, which is defined along shorelines from the significant wave height and a mean period. The empirical proportionality factor is found to reproduce accurately the variations of free IG wave energy in coastal areas, where it was calibrated, and also has a good skill at global scales. In the open ocean, the model is particularly verified for frequencies in the range 5 to 14 mHz for which ocean bottom records are sensitive to the IG signal. The model captures between 30% and 80% of the variance in IG wave heights, depending on...
Tipo: Text Palavras-chave: Infragravity waves; SWOT; Spectral model.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00181/29272/28639.pdf
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How ocean waves rock the Earth: two mechanisms explain microseisms with periods 3 to 300 s ArchiMer
Ardhuin, Fabrice; Gualtieri, Lucia; Stutzmann, Eleonore.
Microseismic activity, recorded everywhere on Earth, is largely due to ocean waves. Recent progress has clearly identified sources of microseisms in the most energetic band, with periods from 3 to 10 s. In contrast, the generation of longer-period microseisms has been strongly debated. Two mechanisms have been proposed to explain seismic wave generation: a primary mechanism, by which ocean waves propagating over bottom slopes generate seismic waves, and a secondary mechanism which relies on the nonlinear interaction of ocean waves. Here we show that the primary mechanism explains the average power, frequency distribution, and most of the variability in signals recorded by vertical seismometers, for seismic periods ranging from 13 to 300 s. The secondary...
Tipo: Text Palavras-chave: Hum; Infragravity waves; Numerical model; Microseisms.
Ano: 2015 URL: https://archimer.ifremer.fr/doc/00251/36219/34769.pdf
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Infragravity waves across the oceans ArchiMer
Rawat, Arshad; Ardhuin, Fabrice; Ballu, Valerie; Crawford, Wayne; Corela, Carlos; Aucan, Jerome.
Ocean infragravity (IG) waves are low-frequency waves generated along shorelines by incident seas and swell and with heights of the order of 1 cm in the open ocean. Despite these small amplitudes, they can be of much importance for ice shelf break up and errors in measurements of sea level by future satellite altimeters. A combination of numerical model results and in situ data is used to show that bottom pressure signals in the infragravity frequency band can be dominated by bursts of energy that travel across ocean basins, and can last for several days. Two particularly strong events recorded in 2008 are studied, one in the North-Pacific and the other in the North-Atlantic. It is shown that infragravity waves can travel across whole oceans basins with...
Tipo: Text Palavras-chave: Infragravity waves; DART; Global wave model.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00233/34465/32860.pdf
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Infragravity waves: from driving mechanisms to impacts ArchiMer
Bertin, Xavier; De Bakker, Anouk; Van Dongeren, Ap; Coco, Giovanni; Andre, Gael; Ardhuin, Fabrice; Bonneton, Philippe; Bouchette, Frederic; Castelle, Bruno; Crawford, Wayne C.; Davidson, Mark; Deen, Martha; Dodet, Guillaume; Guerin, Thomas; Inch, Kris; Leckler, Fabien; Mccall, Robert; Muller, Heloise; Olabarrieta, Maitane; Roelvink, Dano; Ruessink, Gerben; Sous, Damien; Stutzmann, Eleonore; Tissier, Marion.
Infragravity (hereafter IG) waves are surface ocean waves with frequencies below those of wind-generated "short waves" (typically be- low 0.04 Hz). Here we focus on the most common type of IG waves, those induced by the presence of groups in incident short waves. Three related mechanisms explain their generation: (1) the development, shoaling and release of waves bound to the short-wave group envelopes (2) the modulation by these envelopes of the location where short waves break, and (3) the merging of bores (breaking wave front, resembling to a hydraulic jump) inside the surfzone. When reaching shallow water (O(1-10 m)), IG waves can transfer part of their energy back to higher frequencies, a process which is highly dependent on beach slope. On gently...
Tipo: Text Palavras-chave: Infragravity waves; Bound wave; Dissipation; Reflection; Sediment transport; Barrier breaching; Seiche; Earth hum.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00417/52876/53800.pdf
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Modélisation des ondes infragravitaires : de l'échelle régionale à l'échelle mondiale ArchiMer
Rawat, Arshad.
Wind-generated surface gravity waves are ubiquitous at the ocean surface. Their period varies between 2 and 25 seconds, with wavelength varying between a few meters to several hundreds of meters. Longer and, lower frequency surface gravity waves, called infragravity (IG) waves, are associated to these short, high frequency wind-generated waves. These infragravity waves have dominant periods comprised between 30 seconds and 10 minutes, and, when they propagate freely, with horizontal wavelengths of up to tens of kilometres, as given by the linear surface gravity wave dispersion relation. Outside of surf zones, the vertical amplitude of these infragravity waves is of the order of 1-10 cm, while the amplitude of wind-generated waves is of the order of 1-10...
Tipo: Text Palavras-chave: Ondes infragravitaires; Modélisation à l'échelle globale; Infragravity waves; SWOT; Global wave model.
Ano: 2015 URL: https://archimer.ifremer.fr/doc/00498/60937/64330.pdf
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Observation of irregular wave transformation in the surf zone over a gently sloping sandy beach on the French Atlantic coastline ArchiMer
Senechal, N; Dupuis, H; Bonneton, P; Howa, H; Pedreros, R.
The dissipation of the sea-swell frequency band energy (nominally 0.09 < f less than or equal to 0.3 Hz) and the distribution of low frequency band energy (nominally 0.005 less than or equal to f less than or equal to 0.09 Hz) on a transect crossing the surf and swash zones of a fine grained, gently sloping barred beach are investigated with data from a five element synchronous pressure sensor line deployed for 8 d. In this paper, we suggest a rational method to determine the frequency cut-off between the low frequency band and the sea-swell frequency band from the cross-shore evolution of the sea surface elevation energy density spectra. Sea-swell wave heights are depth limited, consistent with previous works whereas low frequency wave heights are...
Tipo: Text Palavras-chave: Cross-shore approach; Wave spectra; Wave dissipation; Infragravity waves.
Ano: 2001 URL: http://archimer.ifremer.fr/doc/00322/43331/42896.pdf
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Observations of large infragravity wave runup at Banneg Island, France ArchiMer
Sheremet, Alex; Staples, Tracy; Ardhuin, Fabrice; Suanez, Serge; Fichaut, Bernard.
On Banneg Island, France, very high water-level events (6.5 m above the astronomical tide) have been observed on the western cliff, exposed to large swells from the North Atlantic. The analysis of hydrodynamic measurements collected during the storm of 10 February 2009 shows unusually high (over 2 m) infragravity wave runup events. By comparing runup observations to measurements in approximately 7 m of water and numerical simulations with a simplified nonlinear model, two distinct infragravity bands may be identified: an 80 s infragravity wave, produced by nonlinear shoaling of the storm swell; and a 300 s wave, trapped on the intertidal platform of the island and generating intermittent, low-frequency inundation. Our analysis shows that the 300 s waves...
Tipo: Text Palavras-chave: Infragravity waves; Trapped waves; Storm waves.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00175/28642/27070.pdf
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The Earth's hum variations from a global model and seismic recordings around the Indian Ocean ArchiMer
Deen, M.; Stutzmann, Eleonore; Ardhuin, Fabrice.
The Earth's hum is the continuous oscillations of the Earth at frequencies between 2 and 20 mHz in the absence of earthquakes. The hum strongest signal consists mainly of surface waves. These seismic waves can be generated by infragravity waves propagating over a sloping ocean bottom close to the coast. So far, this theory has only been tested quantitatively using European seismic stations. We use seismic data recorded all around the Indian Ocean together with an ocean wave model that provides time‐frequency varying hum sources. We show that seasonal variations of the hum sources are smaller in the southern hemisphere (SH) than the northern hemisphere (NH). Using these sources, we model Rayleigh wave RMS amplitudes in the period band 3.5‐20 mHz, and the...
Tipo: Text Palavras-chave: Seismic hum; Infragravity waves; Indian Ocean; Seismic noise; Hum sources; Modeling.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00455/56678/58435.pdf
Registros recuperados: 8
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