摘要
文中讨论了非纬向非平行基流中的对称不稳定，得到了新的非纬向基流下对称不稳定的判据条件。在存在横向切变时，无旋层结流体中扰动的不稳定条件为Ｒｉ＜１４ｓｉｎ２（β－α）；而在有旋层结流体中，弱的横向切变在取一级近似时并不能改变对称不稳定的增长率，但扰动必定传播，传播方向是顺切变方向，波长越短，传播速度越快。
Symmetric instabilities of non zonal and non parallel mean flows are discussed in this paper by using of nonhydrostatic equilibrium mode on a f plane in which sonic wave is filtered under anelastic assumption. The new condition of symmetric instability of non zonal mean flows has been found. In consideration of the shear of mean flows across the band disturbance, the instability condition of non rotation stratified fluid is Ri<14 sin 2 (β-α). The weak shear of mean flows across the band disturbance can't change the growth rate of symmetric instability in rotation stratified fluid under O(ε) approximation. The disturbance must propagate along downshear. The shorter the wavelength is, the bigger the phase velocity is.
出处
《气象学报》
CSCD
北大核心
1998年第2期154-165,共12页
Acta Meteorologica Sinica
基金
国家自然科学基金
关键词
对称不稳定
非纬向基流
非平行基流
气流
Symmetric instability, Non zonal mean flow, Non parallel mean flow.
