经典Ekman流,Ekman层的平衡风场及其扰动稳定性

本文首先利用变分方法,考察了边界层运动能量的变化,指出经典Ekman流是在不可压缩条件下,能量积分达最小值时的一种平衡运动。这对Ekman层运动的物理本质有了进一步的认识。其次,讨论了Ekman动量近似下的Ekman层的平衡风场特征,研究了该平衡风场附近扰动的稳定性问题,结果表明,在自由大气气压场不发生扰动条件下,Ekman层中存在一类新的与惯性不稳定相类似的动力不稳定,且其不稳定性可与Ekman抽吸相联系,还讨论了一般性条件下的扰动不稳定性问题。

CLASSICAL EKMAN FLOW,EQUILIBRIUM WIND AND STABILITY OF DISTURBANCE IN EKMAN LAYER

In this paper, the dynamics of energy chang has been studied with the vari-ational method. The classical Ekman flow is the equilibrium motions in the boundary layer under the conditions of the incompressible and the minum energy The dynamics of the equilibrium wind under the Ekman momentum approximation in the boundary layer is discussed. The stability of disturbance around the equilibrium one is studied. A new kind of instability in the Ekman layer, which is similar to the intertial instability, without disturbance of the pressure filed is suggested. It relates to the Ekman pumping. Besides, a new stability criteria under the general is given.