Effects of an Artificial Sea Slick upon the Atmosphere and the Ocean

Abstract

Vertical mean wind profiles, hot-film data, and wave height data measured during the passage of an artificial sea slick are compared with similar measurements without a sea slick. The effects of the slick are modifications of profile roughness length z₀, and a possible increase in mean wind speed. Power spectral density plots of wave records obtained before, during and after the slick show wave energy modifications for wavelengths up to 10 m. Coherence values computed from a cross-spectral density of the wind field and simultaneously measured wave field both during and after the slick demonstrate the importance of small waves to air-sea interaction processes. Phase angles indicate the maximum horizontal velocity occurs over the wave trough for all spectral components, some of which are above and some below the wind-wave “matched layer.” During a stick, however, the horizontal velocity maximum occurs over the wave crest for those waves remaining coherent with the wind field.