HR: 1300h
AN: SM52A-0564    [PDF]
TI: The Contribution of Ionospheric O$^+$ Ions to the Storm-time Ring Current
AU: * Peroomian, V
EM: vahe@igpp.ucla.edu
AF: UCLA-IGPP, Box 951567, Los Angeles, CA 90095-1567 United States
AU: El-Alaoui, M
EM: mostafa@igpp.ucla.edu
AF: UCLA-IGPP, Box 951567, Los Angeles, CA 90095-1567 United States
AU: Ashour-Abdalla, M
EM: mabdalla@igpp.ucla.edu
AF: UCLA-IGPP, Box 951567, Los Angeles, CA 90095-1567 United States
AU: Zelenyi, L M
EM: lzelenyi@iki.rssi.ru
AF: Space Research Institute, Profsoynaia Str 84/32, Moscow, 117997 Russian Federation
AB: We have investigated the population of the near-Earth plasma sheet and ring current by ionospheric O$^+ $ ions by tracing particle orbits in time-dependent electric and magnetic fields obtained from a three-dimensional global magnetohydrodynamic (MHD) simulation of a geomagnetic storm that occurred on September 24 - 25, 1998 (Dst = -225). During this storm, which began with the impact of a 13 nPa pressure pulse on Earth's magnetosphere shortly before midnight on September 24, 1998, the POLAR spacecraft observed significant outflows of O$^+ $ ions in response to the pressure pulse. We developed a time-dependent empirical map of the ionospheric O$^+ $ ion outflow for this event and calibrated the outflow rate to that observed by the POLAR spacecraft. Ions from the auroral zone were launched in a broad energy range from 500 eV to 10 keV to simulate outflowing ion beams and conics. Since the inner boundary of the MHD simulation is at a radial distance of 4 R$_E$, the ions were launched with the energies typical of those found after acceleration by the auroral parallel electric fields. Dayside ions were launched with energies similar to those found on POLAR/TIDE and POLAR/TIMAS for this event, in the range 100 eV to 1.2 keV. Ions were launched at 10 key times during the storm. We will present time-dependent maps of O$^+ $ plasma moments in the equatorial plane, including density, pressure, temperature, energy density, and current density for this event.
DE: 2730 Magnetosphere--inner
DE: 2744 Magnetotail
DE: 2760 Plasma convection
DE: 2778 Ring current
DE: 2788 Storms and substorms
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting