Relations Of The Outbreak Of The Magnetic Tail Of The Overall Flow (bbf) In Low-latitude Pi2 Pulsation

In chapter 1,we review the background knowledge of Geomagnetic Micropulsations. Briefly, we show the classification of geomagnetic micropulsations, narrative the morphologic characters of each type of pulsations, and then introduce some theoretical studies on Pi pulsations. In chapter 2, we focus our study on Pi2. We divide the space around the earth into several specific regions. Then we study the characters and mechanisms of Pi2 in each region. In chapter 3, we show that there is a close correlation between BBF and mid-low latitude Pi2s. In this chapter, by using the data of Cluster, TC-1/DSP and six ground stations (3 from China and 3 from Europe), we analyze three BBF events that accrued during quiet times from 1700UT to 1930UT on October 22, 2004. It is found that two of BBF events can excite Pi2s. The characteristics of relevant Pi2s are consistent with those of previous studies. However during the third BBF event, both ground and space observations show that there are no Pi2s.In addition, we also check the data from GOES10 , GOES12 and the station chain in Canada. We get the same result as the study's above. Thus it can be concluded that not all BBFs can excite Pi2s.