Numerical study of the McIntyre instability around Gaussian floating vortices in thermal wind balance

Abstract

The visco-diffusive McIntyre instability (McIntyre 1970) has been suggested as a possible source for density layer formation around laboratory and oceanic vortices. This suggestion is here quantitatively addressed using idealised, axisymmetric, numerical simulations of a simple Gaussian-like vortex in thermal wind balance, floating in a rotating, stratified flow. Numerical simulations are complemented by a local stability analysis derived from the seminal study (McIntyre 1970). It is confirmed that the McIntyre instability is responsible for the layering observed around laboratory vortices, but its relevance for explaining layering around meddies remains doubtful.