Equatorward Energy Cascade, Critical Latitude, and the Predominance of Cyclonic Vortices in Geostrophic Turbulence

Abstract

Geostrophic turbulence exhibits features similar to those observed in the oceans: a movement of energy toward the equator, a critical latitude below which are alternating zonal flows and above which the flow is largely isotropic, and a predominance of cyclonic vortices above the critical latitude. These features arise in geostrophic turbulence when the latitude dependence of the deformation radius is taken into account. With the aid of a quasigeostrophic one-layer numerical model, this paper proposes physical mechanisms giving rise to these features.