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M. L. McAllister and T. S. van den Bremer

1. Introduction Wave-following buoys are commonly used as devices to measure free surface elevation in the oceans. This is, in part, owing to their relative ease of installation; unlike the majority of Eulerian measurement devices, buoys do not require a supporting structure. Measurements made with both buoys and Eulerian devices are used in operational oceanography and ocean engineering in various forms. Summary statistics such as significant wave height H s and peak period T p are

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M. L. McAllister and T. S. van den Bremer

1. Introduction Wave-following measurement buoys are widely deployed across the oceans, as they provide a cost effective, easy-to-install alternative to their Eulerian counterparts. As a result of this, they represent an abundant source of data and metocean statistics, outnumbering Eulerian observations by an order of magnitude ( Christou and Ewans 2014 ). However, within the oceanographic community, it is generally perceived that the measurements these devices produce are less accurate

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Fabrice Ardhuin, Erick Rogers, Alexander V. Babanin, Jean-François Filipot, Rudy Magne, Aaron Roland, Andre van der Westhuysen, Pierre Queffeulou, Jean-Michel Lefevre, Lotfi Aouf, and Fabrice Collard

1. Introduction a. On phase-averaged models Spectral wave modeling has been performed for the last 50 years, using the wave energy balance equation ( Gelci et al. 1957 ). This approach is based on a spectral decomposition of the surface elevation variance across wavenumbers k and directions θ . The spectra density F evolves in five dimensions that are the two spectral dimensions k and θ , the two physical dimensions of the ocean surface (usually longitude and latitude), and time t

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Roger Grimshaw, Efim Pelinovsky, and Tatiana Talipova

1. Introduction It is well known that the stable background density stratification of the ocean interior allows for the vertical propagation of internal waves (e.g., Gill 1982 ). Furthermore, this process has been studied experimentally in the laboratory (e.g., Stevens and Imberger 1994 ). Moreover, it is also well known that a monochromatic internal wave is an exact solution of the fully nonlinear Euler equations for an unbounded stratified fluid (in the Boussinesq approximation) with a

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Yuri V. Lvov, Kurt L. Polzin, Esteban G. Tabak, and Naoto Yokoyama

1. Introduction Wave–wave interactions in continuously stratified fluids have been a subject of intensive research in the last few decades. Of particular importance is the observation of a nearly universal internal-wave energy spectrum in the ocean, first described by Garrett and Munk ( Garrett and Munk 1972 , 1975 ; Cairns and Williams 1976 ; Garrett and Munk 1979 ). However, it appears that ocean is too complex to be described by one universal model. Accumulating evidence suggests that

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Hitoshi Tamura, Takuji Waseda, Yasumasa Miyazawa, and Kosei Komatsu

1. Introduction When random or directional ocean waves propagate through a current field that varies spatially, their statistical properties, such as significant wave height or mean wave direction, can be modulated. In general, changes in wave characteristics are attributed to physical processes of wave refraction and/or straining ( Holthuijsen and Tolman 1991 ) caused by the horizontal shear current. Recent studies using spaceborne altimeter data have indicated that strong ocean currents, such

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William J. Plant

1. Spectral conversions Ocean wave height variance spectra can be functions of either wavenumber or frequency. We refer to the first as the wavenumber spectrum and the second as the frequency spectrum. In a recent paper, I briefly mentioned that the peak of the frequency spectrum (  f p ) cannot in general be related to the peak of the wavenumber spectrum ( k p ) by the ocean wave dispersion relationship ( Plant et al. 2005 ). Unfortunately, this fact does not seem to be widely recognized

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Takuji Waseda, Takeshi Kinoshita, and Hitoshi Tamura

1. Introduction Advancement in the understanding of freak waves has led people to rethink the nature of the ocean waves in deep water. The description of the ocean waves, by a self-similar wave spectrum that downshifts due to four-wave resonant interaction, seems robust. However, the generation of the freak wave is suggested to be associated with the abnormally narrow wave spectrum. Recent numerical and experimental studies provide evidence that the quasi-resonant interaction is at work when

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E. J. Walsh, C. W. Wright, M. L. Banner, D. C. Vandemark, B. Chapron, J. Jensen, and S. Lee

1. Introduction For the Southern Ocean Waves Experiment (SOWEX; Banner et al. 1999 ; Chen et al. 2001 ; Walsh et al. 2005 ), conducted in June 1992 out of Hobart, Tasmania, the NASA Scanning Radar Altimeter (SRA; Walsh et al. 1996 , 2002 ; Wright et al. 2001 ) was shipped to Australia and installed on the CSIRO Fokker F-27 research aircraft, instrumented to make comprehensive measurements of air–sea interaction fluxes. The SRA swept a radar beam of 1° half-power width (two way) across the

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Göran Broström, Kai Håkon Christensen, and Jan Erik H. Weber

1. Introduction That surface waves give rise to a net mass transport, or wave drift, has been known for over 150 years ( Stokes 1847 ). Nevertheless, there is still an ongoing discussion on how the mass transport, and the associated momentum flux, should be incorporated into ocean models of various complexities. Several recent papers have provided a variety of descriptions ( Ardhuin et al. 2004 ; Lane et al. 2007 ; McWilliams and Restrepo 1999 ; McWilliams et al. 2004 ; Mellor 2003 ; Weber

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