Wind Sea Growth and Dissipation in the Open Ocean

Abstract

Wind sea growth and dissipation in a swell-dominated, open ocean environment is investigated to explore the use of wave parameters in air?sea process modeling. Wind, wave, and whitecap observations are used from the Gulf of Alaska surface scatter and air?sea interaction experiment (Critical Sea Test-7, Phase 2), conducted 24 February through 1 March 1992. Wind sea components are extracted from buoy directional wave spectra using an inverted catchment area approach for peak isolation with both wave age criteria and an equilibrium range threshold used to classify the wind sea spectral domain. Dimensionless wind sea energy is found to scale with inverse wave age independently of swell. However, wind trend causes significant variations, such as underdeveloped seas during rising winds. These important effects are neglected in wind-forced air?sea process models. The total rate of wave energy dissipation is conveniently estimated using concepts from the Phillips equilibrium range theory. Replacing wind speed with wave dissipation rate in the standard power-law description of oceanic whitecap fraction decreases the range of data scatter by two to three orders of magnitude. The improved modeling of whitecaps demonstrates that wave spectral parameters can be used to enhance air?sea process models.