On the formation of streaks on wind-driven water surfaces

Evidence derived from numerical experiments is presented to show that, contrary to the prevalent notion, the generation of elongated wind-induced streaks on water surfaces with spacing of centimeters is not necessarily attributed to interactions between surface waves and the shear current. Although the water surface is artificially designated as a flat boundary in the numerical simulations here, high-speed streaks appear on the surface arising from an underlying shear current. Floating Lagrangian tracers cluster along the streaks and, in accordance with field and laboratory observations, undergo dislocation and amalgamation.