Turbulence generation by large-scale extreme vertical drafts and the modulation of local energy dissipation in stably stratified geophysical flows

Abstract

Stratified flows can develop powerful vertical drafts - resulting from a resonant interaction of gravity waves and turbulent motions - when the system explores a certain region of the parameter space which is of geophysical interest. These extreme drafts (detected through the kurtosis of the vertical velocity, ${K}_{w}$) do generate turbulence, leading to enhanced local-in-time-and-space kinetic (${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\ensuremath{\epsilon}}}_{V}$) and potential energy dissipation. They are needed in order for stratified flows to be as efficient as homogenous isotropic turbulent flow in dissipating the energy.