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- Development of a bimodal structure in ocean wave spectra
- Toffoli, A.; Onorato, M.; Bitner-Gregersen, E. M.; Monbaliu, J.
- 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.
- Publication type
- Journal article
- Journal of Geophysical Research: Oceans, Vol. 115 (Mar 2010)
- Publication year
- FOR Code(s)
- 0201 Astronomical and Space Sciences; 0404 Geophysics; 0909 Geomatic Engineering
- Directional distribution; Ocean waves; Spectral peaks; Wave energy
- American Geophysical Union
- Publisher URL
- Copyright © 2010 American Geophysical Union. Published version of the paper reproduced here in accordance with the copyright policy of the publisher.
- Research Projects
Oceanic conditions within extreme tropical cyclones, Australian Research Council grant number LP0883888
- Full text
- Peer reviewed