Localized coherence of freak waves
Other literature type, Article
Latifah, Arnida L.
Van Groesen, E.
- Publisher: Copernicus Publications
(issn: 1607-7946, eissn: 1607-7946)
Geophysics. Cosmic physics | Q | Science | Physics | QC1-999 | QC801-809
This paper investigates in detail a possible mechanism of energy convergence
leading to freak waves. We give examples of a freak wave as a (weak)
pseudo-maximal wave to illustrate the importance of phase coherence. Given a
time signal at a certain position, we identify parts of the time signal with
successive high amplitudes, so-called group events, that may lead to a freak
wave using wavelet transform analysis. The local coherence of the critical
group event is measured by its time spreading of the most energetic waves.
Four types of signals have been investigated: dispersive focusing, normal
sea condition, thunderstorm condition and an experimental irregular wave.
In all cases presented in this paper, it is shown that a high correlation
exists between the local coherence and the appearance of a freak wave. This
makes it plausible that freak waves can be developed by local interactions of
waves in a wave group and that the effect of waves that are not in the
immediate vicinity is minimal. This indicates that a local coherence
mechanism within a wave group can be one mechanism that leads to the
appearance of a freak wave.