Influence of cusp O+ outflow on magnetotail dynamics in a multifluid MHD model of the magnetosphere

Abstract

A multifluid version of the Lyon‐Fedder‐Mobarry global simulation model has been used to investigate the effects of outflowing ionospheric O+ on the magnetosphere‐ionosphere system. To quantify these effects, we specify the number density, upward parallel velocity, and temperature of the O+ outflow in a limited area of the low‐altitude simulation boundary representing the projection of cusp, cleft, and low‐latitude boundary layer. A baseline simulation without O+ outflow is compared with simulations with a range of fluxes and initial velocities. In the cases with high fluxes, it is shown that the configuration of the magnetosphere is dramatically changed. In particular, the cross‐polar cap potential is reduced, the polar cap area is increased, and the nightside reconnection line is moved earthward. Furthermore, in one case, the O+ outflow leads to the onset of a second substorm not seen in the other simulation runs.