Spectral Analysis of Nonlinear Water Waves Based on the Hilbert-Huang Transformation

The Hilbert-Huang transformation (HHT) is a new method for analyzing nonlinear and non-stationary data series. The central idea behind the HHT is the so-called empirical mode decomposition (EMD) that numerically decomposes a time-dependent signal into its own underlying characteristic modes. Applying the Hilbert transformation (HT) to each of these disintegrated intrinsic mode function (IMF) subsequently provides the Hilbert amplitude or energy spectrum—producing more accurate spectra and proposing in all probability entirely new physical insights of nonlinear and nonstationary processes. The present paper describes the application of the HHT concerning the spectral frequency analysis of nonlinear transient water waves.