On Zonal Jets in Oceans

TL;DR

This paper explains the formation of alternating zonal jets in oceans as a result of turbulence energy being arrested by free Rossby waves, redirecting energy into zonal modes, a mechanism similar to that in Jovian atmospheres.

Contribution

It demonstrates that the mechanism for jet formation via Rossby waves applies to oceanic contexts despite boundary differences.

Findings

Zonal jets form due to turbulence arrest by free Rossby waves.

The mechanism is robust even with ocean boundaries.

Energy is redirected into zonal modes, explaining observed jets.

Abstract

We find that in parameter regimes relevant to the recently observed alternating zonal jets in oceans, the formation of these jets can be explained as due to an arrest of the turbulent inverse-cascade of energy by {\em free} Rossby waves (as opposed to Rossby {\em basin} modes) and a subsequent redirection of that energy into zonal modes. This mechanism, originally studied in the context of alternating jets in Jovian atmospheres and two dimensional turbulence in zonally-periodic configurations survives in spite of the presence of the meridional boundaries in the oceanic context.