非均匀层结大气中的重力惯性波及其激发对流的物理机制

INTERNAL INERTIA GRAVITY WAVES IN A NON - UNIFORMLY STRATIFIED ATMOSPHERE AND THEIR ROLE IN INITIATING CONVECTION

本文用wKBJ方法求解Boussinesq近似下的重力波方程,导出非均匀层结大气中重力惯性内波的一个守恒波作用量(称为广义波作用量)。根据广义波作用量守恒原理,着重讨论了重力惯性内波在发展过程中尺度变化的规律;在适当的条件下,重力波随着其尺度的变化而可能崩溃(或破碎),从而激发对流的发展。

A wave action density has been derived from a linearized Boussinesq system for inertia gravity waves by use of WKBJ method. The characteristics of the evolu -tion of the waves have been investigted based on the principle of the conservation of the wave action density defined in this paper. The results showed that the developing waves are characterized by the decrease of the horizontal wave length L and the increase of the vertical wave length D. Once the horizontal wave length L has been reduced to a value less than a critical wave length Lc the wave tends to break down and convectve activity may be excited as a result of the breakdown of the waves. The environment conditions favoring the development of the waves are also the conditions favoring the break down of waves and the occurence of convective activity. The effect of the environment condition(varying stratification) on the development of the inertia gravity waves has been discussed in relation to the spatial scale changes of the waves.