WIND STRESS FROM WAVE SLOPES USING PHILLIPS EQUILIBRIUM-THEORY

An open ocean, deep water air-sea interaction experiment was conducted in the Gulf of Alaska. Wave amplitude and slope data were measured us ing a WAVEC heave, pitch, and roll buoy that was let drift in the Alas ka gyre. Wind stress estimates were obtained from a fast-sample anemom eter using the dissipation technique and from synoptic measurements th rough a boundary-layer model. The fundamental correlation and predicti ve relationships between wind friction velocity and wave spectral prop erties were established. A comparison of the slope spectrum to simulta neous wind stresses allowed us to estimate the Phillips proposed unive rsal constant beta. Reintroducing this constant beta into the Phillips slope spectrum and using measured slope spectral characteristics, an inferred wind stress was calculated that was shown to agree well with both the dissipation and model stresses thereby validating both Philli ps theory and the boundary-layer model. Any discrepancies with the mod el stresses were attributed to second-order wave age effects. The roug hness length z(0), nondimensionalized by the sea rms wave height, was shown to decrease with wave age in a manner consistent with Kitaigorod skii's functional form. A general expression for C-d as a function of wind speed or friction velocity and wave age was proposed and verified with independent data.