Theoretical studies on the interaction between the general circulation and small-scale phenomena.

在所谓的参数化中，我们评估较小尺度现象对所考虑的大尺度运动的影响，通常使用后一个变量。然而，如果我们正确地处理相互作用，方程将变成非线性的，包括小运动修正的大尺度运动的反馈效应，并将导致我们有些困难的情况，因为反馈通常是不可能忽略的，除非它的时间尺度足够长。方程的非线性会引起解的分岔。参数化的思想并不一定涉及这样的考虑。然后，在本工作中，作为建立合理的参数化思想的第一步，我们将平流层垂直一维模型作为一个非线性系统，其中平均纬向流和行星波相互影响，并检查了解的分岔以及对外部强迫的响应。因此，我们成功地合理地回答了诸如为什么行星波在冬末会放大，为什么突然变暖倾向于冬末或早春而不是其他季节等问题。这些现象可以解释为稳定平衡状态之间的过渡，发生在平流层，响应太阳差热的季节变化。我们预计，近年来在重力波参数化方面研究较多的重力波与平均环流的相互作用问题也可能出现类似的情况。

In the so-called parameterization, we evaluate the effects of smaller scale phenomena on the large-scale motion considered, usually with use of the latter variables. However, if we treat the interaction correctly, the equations will become non-linear, including the feed-back effects of the large-scale motion modified by the smaller ones, and will lead us to somewhat difficult situation, because it is generally impossible to omit the feed-back, except the case where its time-scale is sufficiently longer. The non-linearity of equation may cause the bifurcation of solutions. The idea of parameterization does not necessarily involve such a consideration. Then, in this wotk, as the first step toward founding a reasonable idea of parameterization, we have a vertical one dimensional model of the stratosphere as a non-linear system in which the mean zonal flow and planetary waves are mutually affecting, and examined the bifurcation of the solutions and also the response to external forcing.As the result, we have succeeded to answer reasonably or soundly the problems such as why the planetary waves can amplify in late winter, why the sudden warmings prefer late winter or early spring to other seasons and so on. These phenomena can be interpreted as the transitions among stable equilibrium states, occuring in the stratosphere responding to the seasonal change in solar differential heating.We anticipate that similar situations may appear in the prblem of interaction between gravity wave and the mean circulation, which is being intensively studied in recent years with respect to the gravity wave parameterization.