非线性正压亚临界不稳定

A NEW CRITERION OF NONLINEAR BAROTROPIC STABILITY INCLUDING EKMAN FRICTION

中文关键词:  亚临界不稳定  非线性判据  广义能量

英文关键词:Subcritical instability  Nonlinear criterion  Generalized energy

中文摘要:

      文中提出了一个新的广义能量作为Lyapunov函数,导出了包含两个联立不等式的一种新的非线性正压稳定性判据。并指出其中一个不等式是初始扰动振幅小于某一临界值,另一个则是摩擦系数大于另一临界值,前者对后者有很强的约束。该判据表明,在实际大气中对于有限振幅扰动容易产生正压亚临界不稳定,它大大地改进了以前的结果。

英文摘要:

      A new generalized energy is propo sed to act as Ly apuno vfunction and thus a new criterion of nonlinear bar ot ropic stability containing two inequalities is obtained.One of the inequalities is that the initial disturbance amplitude is less than a critical value,and the other is that the frictional coefficient is more than another critical value.The former adds a strong rest riction to the latter,a usual nonlinear stability criterion,thus denoting that the subcritical inst ability easily occurs for a finite-amplitude disturbance in the realatm osphere.The new criterion has great himproved the previous results.