Instability of Solid-Body Rotation of Heton Type

It is traditionally believed that in a liquid of uniform density, an axisymmetric barotropic flow with solid-body rotation is stable. Within the framework of a two-level quasi-geostrophic model, this work shows that this is not in the case of a baroclinic flow with solid-body rotation of the heton type. Such a flow has different directions of rotation at two levels. Due to the vertical velocity shift, this flow is always unstable. This paper develops a linear theory of the instability of such flows both in a model without friction and in a model with Ekman friction. It is shown that, for instability in a model with friction, the horizontal wave number of the disturbance should not exceed a certain critical value. It has been established that instability with respect to longwave disturbances in the model without friction is absolute in nature; i.e., it always exists. The development of instability may be associated with the formation of observed disturbances in the axial zone of intense atmospheric vortices.