On symmetric stability and instability of zonal mean flows near the equator.

Abstract

Observations of longitudinally-averaged zonal flows in the atmosphere and ocean tend to display N-S symmetry about the equator, with a characteristic wind maximum or minimum, and therefore little horizontal wind shear locally near the equator. It is shown that this configuration is required for balanced flow on a sphere to be inertially stable. If dissipation can be neglected, any horizontal wind shear at the equator will cause inertial instability to develop, effectively eliminating the horizontal shear. -from Author