Whitecaps and Momentum Transfer

Abstract

When wind blows over a still water surface the momentum so transferred appears in the form of surface waves and wind drift currents. The flux of momentum τ is generally partitioned into that due to skin friction τ_s (viscous drag) and that due to the form drag of the waves τ_f. A part τ_w of the form drag adds momentum to the surface waves; the rest τ_c acts through the waves to alter the underlying currents. Finally, some of τ_w is continually being lost by the waves through whitecapping τ_b; the rest τ_n produces a net increase of wave momentum.