Gray-scale visualization of wave spectra in an ocean eddy

This paper describes the application of gray-scale or sonogram display techniques to the display of time-evolving wave spectra in an ocean eddy during the passage of several weather systems. The experimental data were collected using nine Lagrangian Ambient Noise Drifting buoys (LANDs) [Risley et al., Lagrangian Ambient Noise Drifters, Proc, OCEANS '94, Vol III, p. 34-9] deployed and monitored in a warm eddy north of the Gulf Stream for two weeks in 1994. Non-directional wave-energy spectra were collected every hour along with several other related parameters, most notably wind speed and direction. Gray-scale plots are shown to provide dramatic visualization of the growth and decay of the various energy spectral components as the wind speed rises and falls at various locations in and near the eddy. Gray-scale plots are also used to highlight the spectral differences between selected buoys on opposite sides of the eddy in order to investigate the effect of water current upon the wave spectral content.