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Ionospheric convection driven by NBZ currentsComputer simulations of Birkeland currents and electric fields in the polar ionosphere during periods of northward IMF were conducted. When the IMF z component is northward, an additional current system, called the NBZ current system, is present in the polar cap. These simulations show the effect of the addition of NBZ currents on ionospheric convection, particularly in the polar cap. When the total current in the NBZ system is roughly 25 to 50 percent of the net region 1 and 2 currents, convection in the central portion of the polar cap reverses direction and turns sunward. This creates a pattern of four-cell convection with two small cells located in the polar cap, rotating in an opposite direction from the larger cells. When the Birkeland currents are fixed (constant current source), the electric field is reduced in regions of relatively high conductivity, which affects the pattern of ionospheric convection. Day-night asymmetries in conductivity change convection in such a way that the two polar-cap cells are located within the large dusk cell. When ionospheric convection is fixed (constant voltage source), Birkeland currents are increased in regions of relatively high conductivity. Ionospheric currents, which flow horizontally to close the Birkeland currents, are changed appreciably by the NBZ current system. The principal effect is an increase in ionospheric current in the polar cap.
Document ID
19870053913
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Rasmussen, C. E.
(Utah State Univ. Logan, UT, United States)
Schunk, R. W.
(Utah State University Logan, United States)
Date Acquired
August 13, 2013
Publication Date
May 1, 1987
Publication Information
Publication: Journal of Geophysical Research
Volume: 92
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
87A41187
Funding Number(s)
CONTRACT_GRANT: NAGW-77
CONTRACT_GRANT: NSF ATM-84-17880
Distribution Limits
Public
Copyright
Other

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