In the WA method, the criterion of

In the WA method, the criterion of wind and swell depends only on the separation parabola calculated by wind speed and direction without consideration of the characteristics of ocean waves themselves. It means that there will be more wave systems contained within the parabola when the wind speed is larger. The theory of this method determines the strong correlation between wind sea and wind speed than the OP method, as can be seen in Fig. 10. The correlation coefficient between wind speed and the significant wave height of wind sea is 0.89 by the WA method in Fig. 10a, while the value is 0.73 by the OP method in Fig. 10b. It is generally considered that there is a close correlation among wind speed, wave height, and wave period in a wind-generated wave system (Hwang et al. 1998). Hwang et al. (1998) simplifies the wave growth function by eliminating the dimensionless energy and fetch parameters, obtaining Eq. (10) based on several groups of experiment data: