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Rotationally-induced Birkeland current systemsRotational effects which are negligible in earth's magnetosphere become dominant in the magnetospheres of the outer planets where they give rise to Birkeland current circuits coupling the ionospheric and magnetospheric motions. The centrifugal force of corotation produces an azimuthal ring current in the magnetosphere while the Coriolis force produces a current parallel to the plasma flow. The acceleration current also becomes significant when deviations from strict corotation are appreciable. In general, none of these currents are divergence-free, and closure is provided by ionospheric conduction currents via connecting Birkeland currents. Thus the ionospheric conductivity regulates magnetospheric motions much as it does in the terrestrial case. The effects of such currents have been clearly observed in the magnetospheres of Jupiter and Saturn. Birkeland current circuits also transmit planetary angular momentum to external sinks such as conducting satellites (e.g., Io), plasma production sites (e.g., the Io torus), and/or the surrounding solar wind (as proposed for Uranus).
Document ID
19840062999
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Hill, T. W.
(Rice University Houston, TX, United States)
Date Acquired
August 12, 2013
Publication Date
January 1, 1984
Subject Category
Geophysics
Accession Number
84A45786
Funding Number(s)
CONTRACT_GRANT: NSF ATM-80-19425
CONTRACT_GRANT: NAGW-168
Distribution Limits
Public
Copyright
Other

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