A Dynamic Roughness Equation and Its Application to Wind Stress Determination at the Air-Sea Interface

A dynamic roughness equation including major wind and wave interaction parameters (wind shear velocity, wave height, and phase velocity) is derived. Because this equation implicitly incorporates the effects of wave steepness, relative water depth, and wind duration and fetch, it may be applied to a wide variety of natural conditions. This equation was used to construct a nomogram which can be utilized to determine the wind stress at the sea surface, given phase velocities, wave heights, and the wind speed at any height in the atmospheric boundary layer. The proposed relationships are verified by the available field and laboratory data under near-neutral atmospheric stability conditions from which the appropriate parameters could be determined.