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Dayside auroral-oval plasma density and conductivity enhancements due to magnetosheath electron precipitation.Demonstration that magnetosheath electrons precipitating into the dayside auroral oval are a significant source of ionization and consequently will lead to electrical conductivity enhancements within the oval. By assuming that the electrons are maintained isotropic by strong pitch-angle diffusion as they precipitate into the ionosphere, the precipitation heat flux can be simply related to solar-wind energy density and consequently to the level of magnetic activity. For quiet solar-wind conditions, the heat fluxes of 1 to 10 ergs/sq cm/sec expected and observed lead to height-integrated Pedersen conductivity enhancements of 4 to 15 mhos. During magnetic storms the conductivity enhancements could increase by a factor of 3 to 5. Since the precipitating electrons are soft, the Hall conductivity enhancements are smaller than the Pedersen conductivity enhancements. For typical electric fields the computed conductivity enhancements lead to field-aligned currents bounding the enhancements in order-of-magnitude agreement with observation. The topside ionosphere should also have a density enhancement over the auroral oval on the dayside.
Document ID
19720045715
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Kennel, C. F.
(Colorado, University; National Center for Atmospheric Research, Boulder, Colo.; California, University, Los Angeles, Calif, United States)
Rees, M. H.
(Colorado, University Boulder, Colo., United States)
Date Acquired
August 6, 2013
Publication Date
May 1, 1972
Publication Information
Publication: Journal of Geophysical Research
Volume: 77
Subject Category
Geophysics
Accession Number
72A29381
Funding Number(s)
OTHER: NSF GP-22817
OTHER: AT(04-3)-34
OTHER: N00014-69-A-0200-4023
OTHER: NGR-05-007-116
OTHER: NSF GA-16290
OTHER: NGR-05-007-190
Distribution Limits
Public
Copyright
Other

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