非线性正压亚临界不稳定

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。

A NEW CRITERION OF NONLINEAR BAROTROPIC STABILITY INCLUDING EKMAN FRICTION

A new generalized energy is proposed to act as Lyapunov function and thus a new criterion of nonlinear barotropic 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 restriction to the latter, a usual nonlinear stability criterion, thus denoting that the subcritical instability easily occurs for a finite-amplitude disturbance in the real atmosphere. The new criterion has greath improved the previous results.