Rossby wave equilibria and zonal jets

TL;DR

This paper investigates how Rossby waves evolve into steady states featuring zonal jets and vortices, using statistical equilibrium equations that extend previous models to include conservation laws.

Contribution

It introduces generalized statistical equilibrium equations for Rossby waves, explaining the formation of jets and vortices in the late-time steady state.

Findings

Jet-like solutions are common in the model.

Large vortices form only with specific background flows.

The equations account for all conservation laws.

Abstract

The problem of coherent vortex and zonal jet formation in a system of nonlinear Rossby waves is considered from the point of view of the late time steady state achieved by free decay of a given initial state. Statistical equilibrium equations respecting all conservation laws are constructed, generalizing those derived previously for 2D inviscid Euler flow. Jet-like solutions are ubiquitous, with large coherent vortices existing only when there is uniform background flow with the precise velocity to cancel the beta effect.