Phenomenology of decaying turbulence beneath surface waves

Abstract

This paper explores decaying turbulence beneath surface waves that is initially isotropic and shear free. We start by presenting phenomenology revealed by wave-averaged numerical simulations: an accumulation of angular momentum in coherent vortices perpendicular to the direction of wave propagation, suppression of kinetic energy dissipation and the development of depth-alternating jets. We interpret these features through an analogy with rotating turbulence (Holm 1996 Physica D. 98, 415–441), wherein the curl of the Stokes drift, ∇ × uS, takes on the role of the background vorticity (for example, (f0 + βy)ẑ on the beta plane). We pursue this thread further by showing that a two-equation mode..