Abstract
In this paper we shall present the spectrum analysis of two kinds of kinetic energy interaction terms, one being the interaction between the zonal flow and a disturbance with a given wave number, and the other the non-linear interaction between the disturbance in question and disturbances of all other wave numbers. It is revealed that the former interaction has no definite period, whereas the latter shows two distinct periods, one each for 10 days and for 20 days.
