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Observations of IMF and seasonal effects in high-latitude convectionStrong interplanetary magnetic field (IMF) and seasonal effects in the convection of nightside ionospheric plasma are described. The findings are based on a statistical analysis of observations made with the Johns Hopkins University/ Applied Physics Lab (JHU/APL) HF radar located at Goose Bay, Labrador. For positive sign of the IMF dusk-dawn component, By greater than 0 the dawn cell is more crescent shaped and the dusk cell more round while for BY less than 0 these pairings of size and shape are reversed. The more extreme crescent /round cell dichotomy is obtained for BY greater than 0. The return flows associated with the crescent-shaped cell dominate at midnight MLT (magnetic local time); the reversal in the zonal velocity in the 67 deg-69 deg lambda (magnetic latitude) interval occurs 2.5 hr earlier in summer than in winter. The maximum effects are obtained on the nightside for the pairings By greater than 0, summer and BY less than 0, winter; the first produces the more structured cell in the morning, the second in the evening, and this cell dominates the return flow at midnight. The difference in the zonal flow reversals for these pairings exceeds 4 hr in MLT.
Document ID
19950063686
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Ruohoniemi, J. M.
(The Johns Hopkins University Applied Physics Lab, Laurel, MD, United States)
Greenwald, R. A.
(The Johns Hopkins University Applied Physics Lab, Laurel, MD, United States)
Date Acquired
August 17, 2013
Publication Date
May 1, 1995
Publication Information
Publication: Geophysical Research Letters
Volume: 22
Issue: 9
ISSN: 0094-8276
Subject Category
Geophysics
Accession Number
95A95285
Funding Number(s)
CONTRACT_GRANT: NSF ATM-91-02316
CONTRACT_GRANT: NAG5-1099
CONTRACT_GRANT: NSF ATM-90-03860
Distribution Limits
Public
Copyright
Other

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