Sensitivity to initial conditions in the merging of two-layer baroclinic vortices

Publisher Website
Google Scholar
Abstract
Merging of geostrophic vortices in a two‐layer stratified fluid is studied by means of direct numerical simulations. It is shown that the influence of density stratification on merging depends strongly on the initial shape of the vortices. When potential vortices are initially confined to the upper layer, with zero potential vorticity in the lower layer, the strength of the stratification is found to have no effect on merging. On the contrary, when the vortices initially have all their relative vorticity in the upper layer, with the lower layer at rest, the merging conditions are radically different. In the latter case, the most striking phenomenon is the pronounced scale selectivity that stratification has on merging. This behavior is provisionally interpreted as a consequence of the different far‐field flow patterns for the different vortex profiles.