Surface wave spectra

Abstract

A classification is made of the different types of wave elevation spectra namely lD time spectra, lD spatial spectra, 2D spatial spectra and 3D space-time spectra. Relations with simple single parameter measures of surface wave slope and significant wave height are also stated. Wave measurement devices are examined, including wave staffs, spar buoys, combined motion and wave-probe devices, Laser and Radar altimeters, the inverted echo sounder, radar scatterometers, stereophotography and Fourier transform photography. Theoretical mechanisms for wave generation are reviewed critically. The state of progress in understanding of the equilibrium spectrum, the re-distribution of wave energy, swell waves and overshoot effect, is examined. Finally an attempt is -made to summarize experimental knowledge, and show where -from an acoustics viewpoint it is incomplete, where from a wave dynamics viewpoint current theory is inadequate and where both might be improved.