Meridional Propagation of Zonal Jets in Ocean Gyres

Abstract

Analyses of both altimetric data and in-situ measurements reveal patterns of meridionally-alternating, nearly zonal, coherent jet-like structures in many of the world ocean basins. In this context, recent Ocean General Circulation Model (OGCM) simulations that resolve such zonal jet-like features show that they also propagate, largely in the meridional direction. To investigate such propagation, a feature that has received scant attention, we consider the behavior of such jets in a two-layer quasi-geostrophic model on a closed mid-latitude basin and forced by a double-gyre wind forcing. In this setup, we find that jets are evident in the baroclinic mode of instantaneous fields, that they propagate largely in the meridional direction, and that the propagation is related to an advective mechanism.