基本气流和大地形对于正压波动的作用

THE EFFECTS OF BASIC FLOW AND TOPOGRAPHY ON THE BAROTROPIC DISTURBANCES

中文摘要:

      本文利用能量变化的观点,分析了正压波动发展的机制。结果表明,大地形的作用只能影响涡度拟能的变化,而不能直接影响动能。但基本气流的特征,对于动能与涡度拟能都起一定的作用。如果基本气流是均匀的而且地形的影响可略,则平均动能和涡度拟能都是守恒的,也就是说,这些量都是有界的。但是在切变气流或者波状基本气流中,波动的发展与基本气流的特征以及波动本身的结构具有非常密切的关系。在一般情况下,动能与涡度拟能就不再是守恒的。在本文中,还对某些简单地形作了分析与讨论。

英文摘要:

      With the view of energy variation, the machanism of evolution of barotropic disturbances is studied in this paper. It is found that the topography can affect only the variation of enstrophy but not the kinetic energy of baratropic disturbances. This is quite different with the effects of shearing of basic flow which do affect both the variation of kinetic energy and enstrophy. If the basic flow is uniform in space and the effect of topography is negligible, the mean kinetic energy and enstrophy averaged in the whole region are bounded. But if the basic flow is non-uniform and is wave-like, the development of disturbances is closely related to the structure of the disturbance. Generally, the kinetic energy and enstrophy are not conservative. The effects of topography with simple profile are also discussed in this paper.