HR: 09:15h
AN: SM31E-06 INVITED    [Abstracts]
TI: Radial Transport of Radiation Belt Electrons in the Vicinity of Geosynchronous Orbit
AU: * Ukhorskiy, A
EM: ukhorskiy@jhuapl.edu
AF: JHU/APL, Applied Physics Laboratory 11100 Johns Hopkins Rd, Laurel, MD 20723, United States
AU: Sitnov, M
EM: sitnov@jhuapl.edu
AF: JHU/APL, Applied Physics Laboratory 11100 Johns Hopkins Rd, Laurel, MD 20723, United States
AB: Earth's outer radiation belt is populated by relativistic electrons that produce a complex dynamical response to varying geomagnetic activity. One fundamental process defining global state of the belt is radial transport of electrons across their drift shells. Radial transport is induced by resonant interaction of electron drift motion with ULF oscillations of electric and magnetic fields and is commonly believed to be a diffusive process. The goal of this paper is the analysis of radial transport due to typical ULF fluctuations in the inner magnetospheric fields. For this purpose a test-particle approach is used in the guiding center approximation. In particular we consider ULF oscillations due to global magnetospheric compressions. It is shown that typical variations in the pressure induce large-scale fluctuations in magnetic and inductive electric fields that produce a substantial impact on relativistic electrons. We show that electron transport in these fields and presumably in the fields due to other ULF mechanisms including field line resonances and magnetosonic waves is controlled by the amplitudes of field fluctuations and their spectral properties. Electron motion becomes stochastic due to overlap of electron populations trapped in the vicinities of drift resonances with adjacent harmonics of the field spectrum. It is shown, however, that in spite of the underlying stochasticity the radial diffusion limit is not fully attainable in the outer radiation belt. This is attributed to the fact that phase correlations in electron motion do not have time to decay due to finite size of the system. As a result collective motion of the outer belt electrons can exhibit large deviations from radial diffusion. Solution of the full Liouville's equation is required for accurate description of radial transport in the belt.
DE: 2720 Energetic particles: trapped
DE: 2753 Numerical modeling
DE: 2774 Radiation belts
DE: 2788 Magnetic storms and substorms (7954)
DE: 4420 Chaos (7805)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting