Internal Instability of Nonparallel Flow on an Equatorial Beta-plane

摘要

A simple theoretical model was developed to investigate the inertial instabilityof zonally nonuniform, nonparallel flow near the equator. The basic state was independent of height and time but included cross-equatorial shear with longitudinal variation, as observed in the tropical mesosphere and elsewhere. Numerical solutions were obtained for the most unstable modes. It is shown that, in addition to previously known 'global' (symmetric and nonsymmetric) modes of inertial instability, there exist 'local' modes within regions of anomalous potential vorticity. The local mode has properties similar to those of 'absolute' instability of nonparallel flow as discussed elsewhere in fluid dynamics.... Inertial instability, Equatorial inertia-gravity waves.