The second-order shear of the basic flow represents an instable factor for the symmetric disturbance, and drives the unstable mesoscale disturbance to travel in the meridional direction;

基流二次切变对于中尺度对称扰动来说是一个不稳定因子，并且驱动不稳定的中尺度对称扰动在南北方向传播；

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This paper discusses the stability of internal inertial gravity wave in the heterogeneous stratified atmosphere when basic flow appears to be weak vertical shear by the WKB method.

本文应用WKB方法研究了在弱非均匀层结大气中，当基本气流具有弱垂直切变时，重力惯性内波的稳定性问题。

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When the motion of the basic state is the shear flow (or the differential rotation), this property means that the unstable waves would evolve automatically into the quasi-stationary stage.

当基态运动为剪切流(或较差旋转)时，这一性质将使不稳定波自动演化到准稳阶段。

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