X line distribution determined from earthward and tailward convective bursty flows in the central plasma sheet

摘要

With TC-1, Cluster, and Geotail observations, we statistically analyzed earthward and tailward convective bursty flows (CBFs) from 7 to 31 RE to understand the distribution of X lines in the magnetotail. We also analyzed the effect of the solar wind condition on the X lines with ACE satellite observations. The statistical results show that the earthward CBFs can be distributed widely, from 7 to 31 RE. TC-1 exploration shows that tailward CBFs with negative B_z in the central plasma sheet can seldom be observed inside 13 RE. Tailward CBFs with negative /3, are mainly distributed outside 17 RE, thus indicating that near-Earth X lines are most likely to occur outside 17 RE. According to Cluster observations, the occurrence of tailward CBFs has a sudden increase from 17 to 19 RE. Geotail observations show a slow increase of tailward CBFs outside 20 RE. Both Cluster and Geotail observations indicate that the near-Earth X lines could occur inside 20 RE. The solar wind condition has a significant effect on the occurrence of the X line in the magnetotail. The occurrence of the X line can increase under strong solar wind and decrease under weak solar wind.