Ionospheric O⁺ Outflow During Geomagnetic Storms
 

Magnetospheric plasma originates from two primary sources: the solar wind and the ionosphere. While H⁺ ions come from both sources, plasma sheet O⁺ ions are exclusively ionospheric, making them key tracers of ionospheric contributions. During geomagnetic storms, massive solar wind energy input alters plasma sheet composition from H⁺-dominated under quiet conditions to O⁺-dominated during storms. This shift suggests enhanced ionospheric O⁺ outflow during storm times. In this talk, the variation of O⁺ outflow throughout geomagnetic storm phases will be presented, and its dependence on solar wind drivers, solar EUV flux, and seasonal effects will be explained. Also, seasonal interhemispheric asymmetries of O⁺ outflow will be discussed. These asymmetries provide critical insight into magnetosphere-ionosphere coupling and storm-time plasma sheet dynamics.