Driving ionospheric outflows and magnetospheric O <sup>+</sup> energy density with Alfvén waves

TitleDriving ionospheric outflows and magnetospheric O + energy density with Alfvén waves
Publication TypeJournal Article
Year of Publication2016
AuthorsChaston, CC, Bonnell, JW, Reeves, GD, Skoug, RM
JournalGeophysical Research Letters
Pagination4825 - 4833
Date Published05/2016
KeywordsAlfven waves; ion acceleration; Ionosphere; ionospheric outflow; ring current
AbstractWe show how dispersive Alfvén waves observed in the inner magnetosphere during geomagnetic storms can extract O+ ions from the topside ionosphere and accelerate these ions to energies exceeding 50 keV in the equatorial plane. This occurs through wave trapping, a variant of “shock” surfing, and stochastic ion acceleration. These processes in combination with the mirror force drive field-aligned beams of outflowing ionospheric ions into the equatorial plane that evolve to provide energetic O+ distributions trapped near the equator. These waves also accelerate preexisting/injected ion populations on the same field lines. We show that the action of dispersive Alfvén waves over several minutes may drive order of magnitude increases in O+ ion pressure to make substantial contributions to magnetospheric ion energy density. These wave accelerated ions will enhance the ring current and play a role in the storm time evolution of the magnetosphere.
Short TitleGeophys. Res. Lett.

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