Reply to comment by Rae et al. on 'formation of substorm Pi2: A coherent response to auroral streamers and currents'

摘要

[1] The initiation of Pi2 pulsations is often associated with substorm onset, and their generation mechanism has been extensively discussed. Nishimura et al. [2012, hereinafter referred to as N12] performed a multi-event study by using the all-sky imager network and ground magnetometers of the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission [Angelopoulos, 2008; Mende et al., 2008] and showed that expansion-phase auroral intensifications near the poleward edge of the auroral bulge occur quasiperiodically with a one-to-one correspondence to Pi2 pulses. Those auroral intensifications often propagate equatorward as longitudinally narrow auroral forms, which are called auroral streamers. N12 found that auroral zone Pi2 near the streamer meridian is antiphase with midlatitude-equatorial Pi2, and their amplitude peaks occur near peak intensities of the streamers. This phase relation can be explained by a current wedge that quasiperiodically intensifies in association with streamers, which mark the upward field-aligned current portion of the current wedge.