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Ionospheric Convection in the Postnoon Auroral Oval: SuperDARN and Polar UVI ObservationsSuper Dual Auroral Radar Network (SuperDARN) observations, ultraviolet imaging from the Polar satellite (UVI), and particle precipitation data from DMSP satellites have been used to investigate the electrodynamics of the postnoon auroral oval in the Northern hemisphere. We show that: (1) For negative IMF By, the convection reversal (CR) was co-located with the maximum of auroral luminosity, but during positive IMF By the convection reversal was poleward of the auroral oval up to several degrees in latitude; (2) Postnoon auroral oval was associated with a large-scale upward field-aligned current (FAC) of the order of 6x10(exp -7). A m(exp -2) in magnitude (the FAC was inferred from the SuperDARN and UVI data). For negative IMF By, maximum of the auroral intensity coincides in latitude with the maximum of the upward field-aligned current. However, for positive IMF By. the maximum of the upward FAC was shifted to the poleward edge of the auroral oval; (3) In response to the IMF By turning from positive to negative, the maximum of the auroral luminosity did not change its position noticeably, but the position of the convection reversal changed considerably from 80-81 degs to about 76 degs MLAT, and the maximum of FAC moved from 77-78 degs to about 76 degs MLAT. Thus, after IMF By turns negative, both the FAC maximum and CR tend to coincide with the auroral maximum; (4) The IMF Bz positive deflection was followed by a decrease in both field-aligned current intensity and auroral luminosity. However, the decrease in the auroral luminosity lags behind the FAC decrease by about 12 min. Firstly, these observations allow us to suggest that the IMF By-related electric field can penetrate into the closed magnetosphere and produce convection and FAC changes in the region of the postnoon auroral oval. Secondly, we suggest that the interchange instability is a promising mechanism for the postnoon auroras.
Document ID
20030016695
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Kozlovsky, A.
(Geophysical Observatory Sodankyla, Finland)
Koustov, A.
(Saskatchewan Univ. Saskatoon, Saskatchewan Canada)
Lyatsky, W.
(Alabama Agricultural and Mechanical Univ. Normal, AL United States)
Kangas, J.
(Geophysical Observatory Sodankyla, Finland)
Parks, G.
(California Univ. Berkeley, CA United States)
Chua, D.
(Washington Univ. Seattle, WA United States)
Date Acquired
August 21, 2013
Publication Date
July 22, 2002
Publication Information
Publication: Sodankyla Geophysical Observatory Publications
Issue: 93
ISSN: 1456-3673
ISBN: 951-42-6029-5
Subject Category
Geophysics
Report/Patent Number
Paper-2002JA009261
Funding Number(s)
CONTRACT_GRANT: N00014-97-I-0267
CONTRACT_GRANT: NAG5-10202
PROJECT: Proj. 47918
PROJECT: Proj. 43988
Distribution Limits
Public
Copyright
Other

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