Auroral electrodynamics from simultaneous measurements at high and low altitudes
Abstract
Two auroras sampled nearly simultaneously at high and low altitudes along a field line by the Dynamics Explorer (DE) spacecraft have been used to study auroral electrodynamics. Electric fields plotted as a function of invariant latitude show that the large-scale features are essentially the same at high and low altitudes outside the auroral acceleration region. Parallel electric fields associated with parallel currents are such as to filter out the small-scale structure in the high-altitude electric field pattern. From the magnetic field measurements, we find that there is a return current region embedded between two auroral arc structures. The latitude shift between the high-altitude and low-altitude return current regions indicates that the auroral arcs are moving equatorward with a velocity of about 250 m/s.
Collisionless plasma kinetic theory (Knight, 1973) has been used to predict the relationship between the upward parallel current and the parallel potential drop. The DE 1/DE 2 pair offers a unique Opportunity to test this relationship because the DE 1 spacecraft can measure high altitude plasma parameters without contamination from auroral heating. Using measured values of J
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Citation
Lu, Gang. "Auroral electrodynamics from simultaneous measurements at high and low altitudes." (1991) Diss., Rice University. https://hdl.handle.net/1911/19078.