GEOTAIL observations on the reconnection process in the distant tail in geomagnetically active times

Abstract

A statistical study is made on the reconnection process in the distant tail by using the GEOTAIL observations at x≈ −150 Re and −95 Re in geomagnetically active times with Kp≥3. Occurrence frequencies of various combinations of the field polarity and the convection direction suggest that at least 75% of the reconnection of open field lines occurs inside 150 Re and at least 39% occurs inside 95 Re. At 150 Re the convection of closed field lines constituting the viscous‐like cell is at most 25% of the convection generated by the reconnection of open field lines. The reconnection rate of open field lines varies across the tail and is a few times higher near the tail axis than at the flanks.