A theoretical study of the air-sea drag-saturation in very strong winds

The goal of this note is to provide a theoretical explanation for the saturation of the drag coefficient in strong wind conditions. The hydrodynamic model under consideration takes into account the important effects of airborne droplets of water in a thin layer above the water surface that effectively behave as a different fluid between the water and the air. Above this layer the model is coupled with a log-wind profile for the strong winds blowing above the sea. The main underlying mechanism governing the behavior of the drag coefficient is the Kelvin Helmholtz instability for capillary waves on the water surface and the continuity of shear stress along the intermediate interface.