HR: 0800h
AN: SM31A-01    [Abstracts]
TI: Ring Current Dynamics Using Dipolar, Empirical, or Self-Consistent Magnetic Field Models
AU: * Jordanova, V K
EM: vania@lanl.gov
AF: Los Alamos National Laboratory, Space Science and Applications, Los Alamos, NM 87545, United States
AU: Vapirev, A E
EM: avapirev@cisunix.unh.edu
AF: University of New Hampshire, Space Science Center, Durham, NH 03824, United States
AU: Zaharia, S
EM: szaharia@lanl.gov
AF: Los Alamos National Laboratory, Space Science and Applications, Los Alamos, NM 87545, United States
AB: We use our kinetic ring current-atmosphere interactions model (RAM) that has been recently extended for non- dipolar magnetic field geometry to investigate the effects of various magnetic field models on ring current evolution. In addition, we have coupled our RAM with a 3-D equilibrium model that calculates self-consistently the magnetic field in force balance with the anisotropic ring current distributions. We use this newly improved model to simulate ring current dynamics during several geomagnetic storms and study the mechanisms responsible for the storm-time injection, trapping, and loss of energetic particles. We find that as strong depressions in both the empirical and self-consistent magnetic field develop near Earth on the dusk-to-midnight side during the main phase of a storm, the particles' gradient-curvature drift velocity increases locally several times, while the bounce- averaged hydrogen density decreases significantly. We compare ring current simulations using a self- consistently calculated magnetic field with simulations using either dipolar magnetic field or the empirical magnetic field models of Tsyganenko. In particular, the effect of non-dipolar magnetic field geometry and the feedback of a self-consistently computed magnetic field on ring current dynamics are investigated.
DE: 2720 Energetic particles: trapped
DE: 2730 Magnetosphere: inner
DE: 2753 Numerical modeling
DE: 2778 Ring current
DE: 2788 Magnetic storms and substorms (7954)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Joint Assembly