Role of the Ekman Layers in the Stability of the Symmetric Regime Obtained in a Rotating Annulus

Abstract

The stability of the symmetric regime observed in the rotating heated annulus experiments is investigated. It is shown that the Ekman layers, which have been neglected in previous investigations, are important. In addition to their role in the dissipation of the kinetic energy of the disturbances they induce vertical velocities which can affect the release of the available potential energy necessary for the occurrence of baroclinic instability. The transition curve obtained for marginal stability is in qualitative agreement with the experimental data.