Gyre Turbulence

TL;DR

This paper investigates a 2D wind-driven ocean model showing a turbulent regime where energy dissipation is viscosity-independent, driven by boundary instabilities and characterized by a vortex gas superimposed on a gyre.

Contribution

It introduces the concept of an asymptotic turbulent regime in a 2D ocean model, highlighting boundary instabilities as a key energy dissipation mechanism.

Findings

Energy dissipation becomes independent of viscosity.

Vortex gas coexists with a western-intensified gyre.

Boundary instabilities can evacuate wind energy from large-scale circulation.

Abstract

The exploration of a two-dimensional wind-driven ocean model with no-slip boundaries reveals the existence of a turbulent asymptotic regime where energy dissipation becomes independent of fluid viscosity. This asymptotic flow represents an out-of-equilibrium state, characterized by a vigorous two-dimensional vortex gas superimposed onto a western-intensified gyre. The properties of the vortex gas are elucidated through scaling analysis for detached Prandtl boundary layers, providing a rationalization for the observed anomalous dissipation. The asymptotic regime demonstrates that boundary instabilities alone can be strong enough to evacuate wind-injected energy from the large-scale oceanic circulation.