An efficient method to identify cross-sea states from wave measurements

This paper is aimed at describing a simple and efficient method to identify cross-sea states from directional wave measurements. The method is based on a new parameter named “Cross-Sea Index” (CSI), which is defined as the difference between two distinct definitions of the overall mean wave direction: the classic one introduced by Longuet-Higgins and the more recent one suggested by De Girolamo. In the following, the theoretical basis of the method is firstly outlined. The influence of the directional spectrum characteristics on the Cross-Sea Index is then discussed. Afterwards, the results of two Monte Carlo simulations are shown. These simulations were aimed at testing the new method and at comparing its outcomes with those of three other existing criteria. Finally, the new method is applied to the directional wave measurements, which were recorded by the Italian Sea Wave monitoring Network (SWaN) during the storm on 26th December 1993. All the achieved results clearly show the efficiency of the herein-proposed method.