纬圈平均大气运动特征的振动

本文考虑高度非线性的大气中期运动是一种准涡旋运动,引用了准涡旋观点和方法来处理二维无辐散和三维运动方程,即在开始时保留涡旋项,而在对方程进行纬圈平均后,去掉一些涡旋项,得到了某些大气运动特征如西风指数、纬向动量和涡度的经向输送的纬圈平均值等的变化或摆动的振动方程,并求出谐波解。振动周期决定于经向动能二倍的纬圈平均值的平方根(v2)1/2。基本周期约二十天左右。所得结果可能对极端复杂的大气运动总有出现中期振动的趋势和精致设计的圆盘模拟实验出现摆动的事实,提供某种程度的动力学解释,同时也可能对中期预报的实践提供一些依据。本文的主要科学目的,是想指出对极端复杂的大气中期过程还是可能用线性理论来研究其某些特征的。

THE OSCILLATION OF CERTAIN ZONAL MEAN CHARACTERISTICS OF ATMOSPHERIC MOTION

In this paper, the high non-linear atmospheric motion is considered as a kind of semi-or quasi-eddy motion. By introducing the method of quasi-eddy approximation, i. e., conserving the eddy terms at the beginning and then ignoring some of them after integrating the equations along the latitude circle, the oscillation equations of certain characteristics of atmospheric motion such as zonal index, zonal mean meridional transport of momentum and vorticity and etc. and their harmonic solutions are obtained. The period of oscillation depends on v², a measure of the zonal mean meridional kinetic energy. The period of the first harmonic is about 20 days. The results may probably explain to some extent the oscillation of certain zonal mean characteristics of the observed atmospheric motion and the vacillation of experimental simulation. The main scientific purpose of this paper is to demonstrate that non-linear extended atmospheric processes might he also attacked by even the high linear theory.