Why are the meanders of the North Atlantic current stable and stationary?

Abstract

A simple, 1.5-layer, reduced gravity model of an f-plane jet with a symmetric cross section is employed to explain the stability and stasis of meanders in the North Atlantic Current. The main factors affecting the current's stability are the highly contrasting water masses on both its sides and the current's vertical density structure. The stability and stasis of the NAC results from (1) the near-surface shoaling of the deep isopycnals inshore of the Subpolar Front and (2) a small internal radius of deformation which is due mainly to the small upper-to-lower-layer density difference. In the absence of unstable modes, the dominant wavelength of the meanders is determined by the bathymetry, so the NAC simply follows those contours.