Abstract
The problem of the transition from axisymmetric to nonaxisymmetric flow in a rotating annulus is treated using a simplified version of a two-layer quasi-geostrophic model which is appropriate to an annular region.
The results of the study compare favorably with experimental results of Fowlis and Hide especially with regard to the variation of the transition with viscosity, annular size and depth. They also support an hypothesis made earlier by the author which is that the upper transition is controlled by the boundary layers while the lower transition is controlled by internal dissipation.
