Solar wind directional change triggering large-amplitude deflection of Mercury’s current sheet

The magnetic field and plasma measurements of MESSENGER, which was orbiting Mercury from March 11, 2011 to April 30, 2015, have shown that Mercury’s magnetotail is highly dynamic. Herein, we report on the current sheet (CS) deflection that was observed far away from the magnetic equatorial plane. The typical CS deflection characteristics in Mercury’s nominal lobe region include plasma density increase and multiple negative-to-positive reversals of the X component of the magnetic field. Moreover, a statistical study of the CS deflection in the nominal lobe region is presented. The deflections distributions of the selected 20 cases show a clear dawn-dusk asymmetry and more are cases observed in the dawn sector of Mercury’s magnetotail. The average duration and amplitude of the CS deflection are 142 s and 0.78 R_M , respectively, and they both increase with the distance of the trigger location away from Mercury. Combined with the solar wind data obtained from the WSA-ENLIL model, we propose that these large-amplitude deflections of Mercury’s CS are possibly triggered by the solar wind direction change.