Recurrent dipolarizations of near-Earth magnetotail during high-speed solar wind streamers

Recurrent substorms occur when high-speed solar wind streamers pass by Earth's magnetosphere. Most of the previous researches have been done using the observations obtained at the geosynchronous orbit focusing on the relationship between the solar wind disturbances and the occurrence of substorms. However, it is important to investigate the dynamics of the magnetotail because the magnetotail is the place where substorms develop. In this study we investigated the observations of recurrent dipolarizations in the near-Earth magnetotail that occurred during high-speed solar wind streamers. The dipolarizations and subsequent stretchings have occurred for more than three days with the average period of ~2 - 3 hours. The average period of ~2 - 3 hours is consistent with the average occurrence period of recurrent substorms. Also, the observed signatures on the geosynchronous orbit and the ground show recurrent substorms have occurred during the event. These suggest that the recurrent dipolarizations in the near-Earth magnetotail should be closely related to the recurrent substorms. On the other hand, there was no clear flow activities directly associated with the dipolarizations, except for some intermittent bursty flow activities. We will discuss the detailed characteristics of the dipolarizations and the relationship with recurrent substorms.