The Relation Between the Ring Current and Relativistic Electron Dynamics in
the Earth's Outer Radiation Belt

A.Y. Ukhorskiy (JHU/APL, Laurel, MD 20723), P.C. Brandt, and S. Ohtani

The relativistic electron flux in the Earth's outer radiation belt exhibits
dynamical variations over several orders of magnitude. The most pronounced
changes of the flux are usually associated with geomagnetic storms. The flux
often drops during the main phase of the storm and then rapidly increases
during its recovery phase to the levels sometimes well ex-ceeding the
pre-storm values. One of the primary causes of the observed flux dropouts is
the magnetic field inflation due to the buildup of the ring current.
Subsequently the drift trajectories of relativistic electrons will move
outward and lead to a decrease in the flux observed at geosynchronous. The
goal of this work is to establish the spatio-temporal dependence of the ring
current-radiation belt interactions during geomagnetic storms. The evolution
of the ring current proton fluxes will be derived from the energetic neutral
atom images obtained by the High-Energy Neutral Atom imager on board of the
IMAGE satellite. To couple the ring current buildup to variations in the
radiation belt electron flux at geosynchronous orbit we will use simultaneous
magnetic filed and relativistic electron (>2 MeV) measurements acquired by
GOES 8-12 satellites. The comparative analysis of the data will provide the
local time dependence of the electron flux dropouts on the position of the
ring current maximum and the level of geo-magnetic activity.

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Presentation at the Yosemite Conference of Inner Magnetospheric Interactions,
3 - 6 February 2004, Yosemite, California, USA