Instability of a Convergent Ekman Flow: Part I. Laboratory Experiments

Abstract

A convergent Ekman flow is made by a differential rotation between a rotating annulus and a rigid upper lid, and the instability of a convergent Ekman flow is studied experimentally.
It is shown that unstable waves with different characteristics from well known class A and class B waves exist in a convergent Ekman flow. The unstable waves are destabilized in the flow with the very low Reynolds number (about 1.5) and they extend vertically throughout the fluid layer. These characteristics are similar to those of unstable waves found by Arons et al. (1961).