On the nature of the turbulent energy dissipation beneath nonbreaking waves

Here we have determined the nature of turbulent flow associated with oceanic nonbreaking waves, which are on average much more prevalent than breaking waves in most wind conditions. We found this flow to be characterized by a low turbulence microscale Reynolds number of 30 < Reλ < 100. We observed that the turbulent kinetic energy dissipation rate associated with nonbreaking waves ϵ, ranged to 3 · 10−4 W/kg for a wave amplitude 50 cm. The ϵ, under nonbreaking waves, was consistent with urn:x-wiley:grl:media:grl61303:grl61303-math-0001; Sij is the large-scale (energy-containing scales) wave-induced mean flow stress tensor. The turbulent Reynolds stress associated with nonbreaking waves was consistent with experimental data when parameterized by an amplitude independent constant turbulent eddy viscosity, 10 times larger than the molecular value. Given that nonbreaking waves typically cover a much larger fraction of the ocean surface (90–100%) than breaking waves, this result shows that their contribution to wave dissipation can be significant.