Particle Transport From the Plasma Sheet to the Ring Current Region and Ring
Current Development Under the Influence of Substorm-Associated Electric Fields

N.Y. Ganushkina and T.T. Pulkkinen 
Finnish Meteorological Institute, Helsinki, Finland


The coupling between plasma populations, namely, the ring current and the plasma
sheet, is analyzed in the frame of study on the storm-time ring current response
and development under the influence of substorm-associated electric fields. We
model the proposed periods of April-June 2001 and April 2002 storm. We trace
particles with arbitrary pitch angles numerically in the drift approximation.
Tracing is performed in different realistic time-dependent magnetic and electric
field models. Substorm-associated electric field is given by Gaussian pulse with
azimuthal field component propagating inward with a velocity dependent on radial
distance. The magnetic field from this pulse is calculated by Faraday's law. We
model particle inward motion and energization by a series of electric field
pulses representing substorm activations during storm events. The obtained model
Dst index, energy density and particle flux maps are then compared to
ground-based and satellite observations such as ground-based magnetic field and
IMAGE, LANL, CLUSTER particle measurements. The role of substorm-associated
fields in the energization of the plasma sheet particles to higher energies
(more than 100 keV) and their transport inward to closed drift shells is closely
studied.

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Presentation, Fall A.G.U. Meeting, San Francisco, CA, 13-17 December 2004