We investigate the critical issue on how the BBF (bursty bulk flow) is related to the substorm current wedge formation. Observationally, after analysing data sets from Geotail spacecraft at near tail and many ground magnetic observatories for 9 months period of 1996, we find three BBF events that clearly occurred at the center of the wedge with region I type FAC (field-aligned current), and two other BBF events that were seen outside the wedge sector. Theoretically, we suggest that the substorm current wedge generation by BBF is most likely when the J⊥ · ∇B contribution is dominant in the well-known MHD JII expression (Vasyliunaus, 1984) or when the divergence of the cross-tail current carried by the particle's gradient/curvature drift is predominantly sufficient at the moment of the BBF arrival at near tail.

• 이대영(한국과학기술원 물리학과) | LEE DAE-YOUNG (Physics Department, Korea Advanced Institute of Science and Technology)
• 민경욱(한국과학기술원 물리학과) | MIN KYOUNG WOOK (Physics Department, Korea Advanced Institute of Science and Technology)