Probabilistic modeling of directional and linear characteristics of wind and sea states

The analytic wind and wave climate modeling is important for a variety of ocean engineering applications. Usually, the probabilistic description of the wind and wave regime is confined to the linear characteristics of sea states and wind conditions, i.e., the significant wave height, wave period and wind speed. Rapidly emerging applications, such as offshore wind and wave energy utilization, are largely dependent on the accurate description of the directional wind and wave characteristics of the areas under study. In this work, two analytic bivariate probability models for the joint distributions of: (a) significant wave height-wave direction, (b) wind speed-wind direction and (c) wave direction-wind direction are presented, discussed and applied in detail. The proposed models, which take into consideration the dependence of the corresponding variables and are defined by closed-form relations, are theoretically sound and tractable. Numerical results are provided for three locations along the US coasts, which are characterized by different characteristics of wind and wave climate. The proposed joint distributions elucidate the probabilistic structure of the wind and wave climate patterns and, furthermore, they allow the assessment of the special and important cases of aligned and opposing wind and sea states.