Comparative evaluation of directional wave analysis techniques applied to field measurements

In order to set up an operational data processing program for the analysis of in-situ wave measurements, six directional wave analysis methods are compared for a 'single-point' measuring system. In a previous step of this study, such as comparison had been performed on three different types of directional wave spectra recorded in a laboratory wave basin (Benoit and Teisson, 1994). In the present work, these methods are applied to field measurements by analyzing data from a three-displacements buoy for two different meteorological conditions (swell and local wind-sea). 'Single-point' gauges are found to accurately resolve unimodal spectra when associated to advanced methods (Iterative Maximum Likelihood Method, Maximum Entropy Method, Bayesian Method). This comparative exercise allows to reach a better knowledge of capabilities, limitations and performances of directional analysis methods (including operational aspects such as CPU time) and will serve for the choice of methods for routine analysis.