|
|
|
|
|
| Ardhuin, Fabrice; Lavanant, Thibaut; Obrebski, Mathias; Marie, Louis; Royer, Jean-yves; D'Eu, Jean-francois; Howe, Bruce M.; Lukas, Roger; Aucan, Jerome. |
| The generation of ultra-low frequency acoustic noise (0.1 to 1 Hz) by the nonlinear interaction of ocean surface gravity waves is well established. More controversial are the quantitative theories that attempt to predict the recorded noise levels and their variability. Here a single theoretical framework is used to predict the noise level associated with propagating pseudo-Rayleigh modes and evanescent acoustic-gravity modes. The latter are dominant only within 200 m from the sea surface, in shallow or deep water. At depths larger than 500 m, the comparison of a numerical noise model with hydrophone records from two open-ocean sites near Hawaii and the Kerguelen islands reveal: (a) Deep ocean acoustic noise at frequencies 0.1 to 1 Hz is consistent with the... |
| Tipo: Text |
|
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00176/28748/27211.pdf |
| |
|
|
| Olagnon, Michel; Loubersac, Lionel; Aucan, Jerome. |
| The present article introduces and defines what are the rogue or freak waves. After an historical reminder on the recent consideration of their existence, several events of waves having struck big or small ships or still the coastline are presented. A paragraph is dedicated to the scientific explanation of the phenomenon and the difference with other phenomenons such tsunamis or tidal bores is clarified. After a reminder of the international mobilization towards a forecast system, a conclusion focuses on events met in New Caledonian waters and analyzes more exactly testimonies related to this type of phenomenon by trying to clarify their causes. |
| Tipo: Text |
|
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00186/29724/28142.pdf |
| |
|
|
| 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 |
| |
|
|
| Aucan, Jerome; Ardhuin, Fabrice. |
| Ocean infragravity waves are surface gravity waves with periods of several minutes and corresponding wavelengths of up to tens of kilometers. When propagating freely in the deep ocean, these waves are typically small, several centimeters at most, so they have been seldom studied. In the context of future wide-swath altimetry missions, these waves need to be better quantified as they have wavelengths that will be resolved by such instruments. Here, we analyze the global climatology and variability of infragravity waves in the deep ocean using data from over 40 open ocean locations, with depths larger than 2000 m. We show that typical infragravity wave heights are higher than previously estimated, with winter-averaged values up to 11 mm off the U. S. West... |
| Tipo: Text |
Palavras-chave: Infragravity; SWO. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00166/27753/25942.pdf |
| |
|
|
| 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 |
| |
|
|
|
