The frequency spectrum of Pi 2 micropulsation activity and its relationship to planetary magnetic activity

An analysis of eighteen Pi 2 micropulsation events reveals that the frequency content of each event may contain from one to several relatively narrow band contributions. It is found that the number of components in the frequency spectrum increases linearly with increasing Kp index. It is shown that the minimum period in a Pi 2 event decreases with increasing Kp, while the maximum period in an event increases with increasing Kpuntil Kp ∼ 2o, after which it decreases slightly with further increase in Kp. It is suggested that a combination of auroral activity and magnetic storm activity governs the latitudinal position of the auroral electro jet and thus determines the frequency content of a Pi 2.