A New Method for Obtaining the Directional Spectrum of Ocean Surface Gravity Waves

The measurement of wave height and direction spectra is a classical problem; it has been attempted in a variety of ways with various degrees of success In this paper, the Oceanics Division (formerly National Marine Consultants) of Interstate Electronics Corporation extends these previous efforts, utilizing applicable background work to obtain the desired electronic wave height and direction system. The system basically provides the time history of amplitude and wave slope to allow the two-dimensional wave spectrum to be uniquely computed. For simplicity of thought, the surface of the sea is most easily considered as sinusoidal. However, the statistical and spectral mathematical tools used allow the more random and confused surface characteristics to be taken into account. Efficient processing, recording, reduction, and evaluation of the data thus provide the oceanographer with the desired spectral coefficients related to power density and directional spectra. Typical installations are discussed showing applications to pier or pole mounting as well as deep-moored buoy installations.