Characteristics of the Marine Atmospheric Boundary Layer under the Influence of Ocean Surface Waves

The deviation of the mean wind profile from Monin–Obukhov similarity theory (MOST) within the wave boundary layer (WBL) is investigated by combining four levels of turbulence data measured on a fixed platform with wave measurements. The data suggest that the mean wind profile follows MOST under wind-sea conditions because the turbulence statistics and structure are consistent with the attached eddy model. However, pronounced swell-related peaks appeared in the velocity spectra and uw cospectra under swell conditions. The upward wave-induced stress resulted in a large wind gradient within the WBL when light winds traveled with the swell, while the opposite result was found for the wind-opposite swell. These phenomena were analyzed based on the velocity spectra and turbulence variances. We found that the deviation of the wind profile was due to the longer or shorter length of the f −1 scaling region appearing in the velocity spectra.