Local Energy Spectra in the Vicinity of an Extreme Wave Event

Previous work by Baldock, Swan and Taylor [1], Johannessen and Swan [2,3], and Bateman, Swan and Taylor [4,5] has demonstrated that in the vicinity of an extreme wave event there are significant and rapid changes in the local wave spectrum. The present paper combines two recent advances. The first is a new fully nonlinear directional wave model, the application of which is particularly suited to the description of extreme waves arising in realistic sea states. The second involves recent advances in time-frequency analysis techniques. Unlike traditional spectral analysis, based upon the Fourier transform, these allow local and rapid changes in a wave spectrum to be clearly identified. By combining these methods the proposed paper will first highlight the occurrence of these changes in realistic seas and will subsequently demonstrate their significance both in terms of estimating crest height elevations and in predicting the associated water particle kinematics.