Wave Transformation during Extratropical Storm

Abstract

Wave observations made during an October 1990 storm on the North Carolina coast are used to investigate the evolution of wind waves as they propagate from about 48 m to 8.5 m of water. The observations include height, period, and direction as well as frequency and directional spectra. The wave measurements are separated by 90 km with simple bathymetry. During the active wind-sea growth (winds of 25 m/s), spatial and temporal changes in the wave field indicate that a quasi-steady-state assumption is no longer valid. Later, the wave field becomes a mixture of two wave systems: swell out of the northeast and a wind-sea system from the northwest. It is concluded that even for a relatively simple storm, evaluation of the physical mechanisms and prediction require a time-dependent numerical model.