The generation and decay of wind waves in deep water

Abstract

Data on the generation and decay of wind‐generated gravity waves have been collected for several years by the University of California. These data, as well as the original data of Sverdrup and Munk, are analyzed and the results presented in dimensionless graphs suitable for use in wave forecasting. The dimensionless parameters presented by Sverdrup and Munk are suitable; however, new curves were constructed which include new data recently available. In order that the data on the decay of waves could be presented in a logical manner, a concept, based upon the following observations, was introduced: (1) Individual waves do not maintain their identity in deep water. (2) A spectrum of lengths and heights is present in both the fetch and decay areas. (3) At any particular decay distance the significant period decreases with time. (4) The significant period increases with decay distance in a manner different from that assumed by Sverdrup and Munk for their decay relationships. (5) Travel time depends upon the group velocity associated with the significant period at the end of the decay distance. It was found that the significant wave height and period at the end of the decay distance depend upon the length of the fetch and the height and period at the end of the fetch as well as upon the decay distance.