长波稳定性的季节变化

SEASONAL VARIATION OF STABILITY OF LONG-WAVES

利用多层模式导得了多层斜压大气中的斜压不稳定的必要条件,还利用迭代-还原法计算了春夏秋冬实际基流上不稳定波的增长率。结果显示,长波扰动的增长率及其不稳定波的波长范围有明显的季节变化,冬季增长率最大,不稳定波的波长范围也最宽,春季次之,夏季最弱;β参数对长波不稳定起稳定化作用,它减小不稳定波的增长率,缩小不稳定波的波长范围;Froude数的影响与β参数相反,它对长波起不稳定化作用.地形的存在,使不稳定波的波长范围缩小,对增长率的影响比较复杂。

Necessary conditions for baroclinic instability in multi-layer baroclinic atmosphere is derived with a multi-layer model and growth rates of unstable waves in real basic flows computed for all four seasons of the year using iteration-reduction method. The growth rate of long wave disturbance is found to be the largest and the wavelength of unstable wave the longest in winter, decreasing as it goes to spring and summer. Parameter 3 stabilizes unstable long waves by reducing its growth rate and wavelength range. Froude number acts in reverse with β, making long waves unstable. Topography tends to reduce the length range of unstable waves while having complex effects on the growth rates.