Fate of outflowing suprathermal oxygen ions that originate in the polar ionosphere

We investigate the transport and ultimate fate of outflowing suprathermal O+ ions by kinetic means using a full-particle tracing scheme. We launched O+ ions in order to determine their final destination in terms of the magnetopause, the distant tail, the ring current (L-shell of 5), and the atmosphere. The number of O+ ions that reached each of the destinations was calculated quantitatively by employing an empirical model of the outflowing ion distribution. This empirical model is based on long-term data from the Suprathermal Ion Mass Spectrometer aboard the Akebono satellite and depends on Kp and the sunspot number. Major results are as follows: (1) Under an active-time magnetic field and a midstrength convection electric field, the majority of outflowing ions with initial speed greater than the escaping speed reached the ring current, with lesser amounts reaching the magnetopause, the distant tail, and the atmosphere. (2) The presence of an active-time magnetic field results in an increase in the number of ions that reach the ring current by a factor of similar to 3, the magnetopause by a factor of similar to 0.5, the distant tail by a factor of similar to 200, and the atmosphere by a factor of similar to 0.01 in comparison with those under a quiet time magnetic field. (3) An energy distribution of ions at L=5 shows that in addition to a thermal/suprathermal component, an energetic component peaking at similar to 20 keV appears for the active condition, which resembles an averaged spectrum of ring current O+ ions.