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Development of a bimodal structure in ocean wave spectra
Toffoli, A.; Onorato, M.; Bitner-Gregersen, E.M.; Monbaliu, J. (2010). Development of a bimodal structure in ocean wave spectra. J. Geophys. Res. 115(C3). dx.doi.org/10.1029/2009JC005495
In: Journal of Geophysical Research. American Geophysical Union: Richmond. ISSN 0148-0227, more
Peer reviewed article  

Available in Authors 
    VLIZ: Open Repository 231072 [ OMA ]

Keyword
    Marine

Authors  Top 
  • Toffoli, A.
  • Onorato, M.
  • Bitner-Gregersen, E.M.
  • Monbaliu, J., more

Abstract
    Traditionally, the directional distribution of ocean waves has been regarded as unimodal, with energy concentrated mainly on the wind direction. However, numerical experiments and field measurements have already demonstrated that the energy of short waves tends to be accumulated along two off-wind directions, generating a bimodal directional distribution. Here, numerical simulations of the potential Euler equations are used to investigate the temporal evolution of initially unimodal directional wave spectra. Because this approach does not include external forcing such as wind and breaking dissipation, spectral changes are only driven by nonlinear interactions. The simulations show that the wave energy spreads outward from the spectral peak, following two characteristic directions. As a result, the directional distribution develops a bimodal form as the wavefield evolves. Although bimodal properties are more pronounced in the high wave number part of the spectrum, in agreement with previous field measurements, the simulations also show that directional bimodality characterizes the spectral peak.

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