ON THE MEASUREMENT OF THE DIRECTIONAL SPECTRA OF WIND GENERATED WAVES USING A LINEAR ARRAY OF SURFACE ELEVATION DETECTORS.
WOODS HOLE OCEANOGRAPHIC INSTITUTION MASS
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Wind generated waves - the disturbance produced by the action of the wind blowing over water - may be described in terms of the distribution of energy amongst various sinusoidal components having different frequencies and different directions of propagation. Well developed techniques and apparatus are available for measuring the directional spectrum of acoustic and radio signals. However technical difficulties which arise because of the very low frequencies of water waves preclude the direct application of these techniques to the investigation of water waves. Consequently, a major concern of this work is the detailed development of a numerical method with which the functions of directional selection and frequency filtering may be performed using a digital computer. A unique feature of this method is that directional information can be obtained from a stationary linear array of surface elevation detectors. The results of a few observations taken in Buzzards Bay Massachusetts are examined in order to demonstrate the internal consistency of the instrument system. These preliminary observations also indicate rather clearly that the directional distribution of spectral energy is neither smoothly distributed nor is it a maximum in the direction of the wind. It is concluded that further investigation is required before this effect can be interpreted physically. Author