HR: 14:55h
AN: SM13C-06    [Abstracts]
TI: Multiscale plasma structuring near the boundary of open-closed field lines
AU: * Ashour-Abdalla, M
EM: mabdalla@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, UCLA, 405 Hilgard Avenue, Los Angeles, CA 90095-1567 United States
AU: * Ashour-Abdalla, M
EM: mabdalla@igpp.ucla.edu
AF: Department of Physics, UCLA, 405 Hilgard Avenue, Los Angeles, CA 90095-1547 United States
AU: Bosqued, J
EM: jean-michel.bosqued@cesr.fr
AF: Centre Etude Spatiale Rayonnements Rayonnements, 9 Ave Colonel-Roche POB 4346/Cedex, Touluse, 31028 France
AU: El-Alaoui, M
EM: mostafa@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, UCLA, 405 Hilgard Avenue, Los Angeles, CA 90095-1567 United States
AU: Peroomian, V
EM: vahe@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, UCLA, 405 Hilgard Avenue, Los Angeles, CA 90095-1567 United States
AU: Walker, R
EM: rwalker@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, UCLA, 405 Hilgard Avenue, Los Angeles, CA 90095-1567 United States
AU: Zelenyi, L
EM: lzelenyi@iki.rssi.ru
AF: Space Research Institute, Russian Academy of Sciences, Profsoynaia Str 84/32, Moscow, 117997 Russian Federation
AU: Wright, J
EM: jwright@cdi.ucla.edu
AF: Department of Physics, UCLA, 405 Hilgard Avenue, Los Angeles, CA 90095-1547 United States
AU: Cheng, A
EM: adrcheng@ucla.edu
AF: Department of Physics, UCLA, 405 Hilgard Avenue, Los Angeles, CA 90095-1547 United States
AB: Magnetospheric plasma is very dynamic and filamented in nature, especially in the vicinity of the separatrix between open and closed field lines in the magnetotail. Dispersed ion structures in which the highest energy ions are found nearest the boundary have been observed in this region by the Aureol-3, Akebono and Interball satellites. They are observed frequently (50% of the time) by the four spacecraft of the Cluster mission, allowing for an improved and more detailed analysis of the spatial and temporal characteristics of these structures. In this study, we examine an inbound plasma sheet boundary layer (PSBL) crossing by the Cluster spacecraft on February 14, 2001. On this day, the Cluster spacecraft observed dispersed ion structures at the poleward edge of the boundary, and "echoes" of these structures at lower latitudes. In addition, each dispersed ion structure was comprised of "beamlets," which are discrete structures in the ion precipitation profile. Previous studies of this event have postulated that these structures are a result of transient burst-like acceleration effects mixed with time of flight effects. We have used a combination of global magnetohydrodynamic simulations and particle trajectory calculations to analyze this event. Our investigation began with a global magnetohydrodynamic (MHD) simulation of Earth's magnetosphere driven by solar wind data from the ACE spacecraft. We then launched distributions of ions representing the fluxes observed by the CIS experiment onboard the Cluster 1, 3, and 4 spacecraft both forward and backward in time from the spacecraft location in the time-dependent global MHD electric and magnetic fields. This allows us to determine the origins and acceleration mechanisms of ions observed by Cluster. By comparing our results from the three spacecraft we can determine the relationship between the multiple structures observed by each spacecraft and separate spatial from temporal acceleration mechanisms. We are especially interested in quantifying the role of non-adiabatic acceleration in the formation of the observed structures.
DE: 2748 Magnetotail boundary layers
DE: 2764 Plasma sheet
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting