A Method for the Automatic Measurement of Wave Frequency

The idea is advanced that the dominant wave frequency in a locally wind-generated sea may be accurately estimated from the ratio of root-mean-square surface vertical velocity to root-mean-square surface deviation. Field and laboratory data are used to establish the relationship between this ratio and the frequency of the peak of the spectrum as a function of inverse wave age. Wave age and the nondimensional fetch parameter are shown to be uniquely related in the fetch-limited case. Finally a procedure is given for estimating the appropriate one-dimensional spectrum from automatic field measurements of average wind speed, root-mean-square surface deviation, and root-mean-square surface vertical velocity.