INJUN 5 Observations of Magnetospheric Electric Fields and Plasma Convection
Recent measurements of magnetospheric electric fields with the satellite INJUN 5 have provided a comprehensive global survey of plasma convection at low altitudes in the magnetosphere. A persistent feature of these electric field observations is the occurrence of an abrupt reversal in the convection electric field at auroral zone latitudes. The plasma convection velocities associated with these reversals are generally directed E-W, away from the sun on the poleward side of the reversal, and toward the sun on the equatorward side of the reversal. Convection velocities over the polar cap region are normally less than those observed near the reversal region. The electric field reversal is observed to be coincident with the ‘trapping boundary’ for electrons with energies e>45 keV. Near local noon the region of anti-sunward convection poleward of the electric field reversal/trapping boundary corresponds to the low altitude extension of the polar cusp plasma. Intense ‘inverted V’ electron precipitation events associated with auroral arcs are also observed near and poleward of the electric field reversal/trapping boundary. These observations are discussed in terms of a current model of magnetospheric convection.
KeywordsConvection Velocity Local Noon Plasma Convection Electric Field Measurement Convection Electric Field
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