The Ion Population of the Magnetotail During the April 17, 2002 Magnetic Storm

We have investigated the proportional population of the magnetosphere by ions of solar wind and ionospheric origin during the April 17, 2002 magnetic storm by using the large-scale kinetic (LSK) particle tracing technique. The three-dimensional, time-dependent magnetic and electric fields for this calculation were obtained from a global magnetohydrodynamic (MHD) simulation that used upstream solar wind and interplanetary magnetic field data from the ACE spacecraft. To study solar wind entry, we launched ions upstream of the bowshock beginning two hours prior to the shock arrival and continuing for eight hours during the sudden storm commencement and the main phase of the storm. Ions were launched with the solar wind streaming velocity and thermal speed measured at that time. The outflow rates and locations of ionospheric H+ and O+ ions were specified by empirical models. For O+ ions, we used the outflow rates specified by Strangeway et al. [2005] and launched ions in accordance to the locations specified by both the Poynting flux and electron precipitation regions. In addition, O+ densities in the near-Earth plasma sheet obtained from the LSK calculations were calibrated with densities obtained by inverting IMAGE/HENA data, allowing us to determine the actual O+ outflow rate throughout this event.