Differences in ionospheric O+ and H+ outflow during storms with and
without sawtooth oscillations
Abstract
Previous simulations have suggested that O+ outflow plays a role in
driving the sawtooth oscillations. This study investigates the role of
O+ by identifying the differences in ionospheric outflow between
sawtooth and non-sawtooth storms using 11 years of FAST/Time of flight
Energy Angle Mass Spectrograph (TEAMS) ion composition data from 1996
through 2007 during storms driven by coronal mass ejections (CMEs). We
find that the storm’s initial phase shows larger O+ outflow during
non-sawtooth storms, and the main and recovery phases revealed
differences in the location of ionospheric outflow. On the pre-midnight
sector, a larger O+ outflow was observed during the main phase of
sawtooth storms, while non-sawtooth storms exhibited stronger O+ outflow
during the recovery phase. On the dayside, the peak outflow shifts
significantly towards dawn during sawtooth storms. This strong dawnside
sector outflow during sawtooth storms warrants consideration.