STABILITY OF COMPRESSIBLE EKMAN BOUNDARY-LAYER FLOW.

The linear stability properties of the Ekman layer in a rapidly rotating gas have been computed numerically. The two types of instability present in an Ekman layer of a homogeneous fluid, which are usually called classes A and B, respectively, are significantly modified by the compressibility. The critical Reynolds number for the class A instability is found to first increase and then decrease for increasing values of the Mach number. The instability waves of class B are monotonically destabilized as the value of the Mach number increases. In addition, a new class of unstable waves appears for a finite value of the Mach number. Refs.