Exploring the influence of ionospheric O+ outflow on magnetospheric dynamics: Dependence on the source location

Abstract

Heavy ions of ionospheric origin (O+) play an important role in altering global magnetospheric dynamics. While the heavy ions mainly originate from the dayside cusp and the nightside auroral region, the impact of these heavy ions on magnetospheric dynamics has not been differentiated. Controversy also remains on the role of heavy ions on tail stability and their energization mechanism in the magnetosphere. Two global MHD simulations are carried out to investigate the influence of heavy ion outflow from different source regions on reconnection rates, tail stability, and ring current energization. The local reconnection rate at the subsolar point and the total dayside reconnection rate are reduced after the outflow begins, but the decrease is more significant when the outflow comes out of the cusp region. Furthermore, the magnetotail is more disturbed when heavy ions flow out of the dayside cusp region as opposed to the nightside auroral zone. This implies that the role of O+ on tail stability is not definitively positive or negative; instead, the location of the source of heavy ions may be important in determining tail dynamics. Finally, the simulation reveals that the heavy ions originating from the dayside cusp region experience first adiabatic heating while traveling from the tail reconnection site toward the Earth and then further energization caused by flow braking near the outer boundary of the ring current. Key Points reconnection rates reduced more when outflow is originated from the cuspheavy ions energized through two steps after tail reconnectiontail stability depends on where the O+ comes out ©2012. American Geophysical Union. All Rights Reserved.