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Geotail Measurements Compared with the Motions of High-Latitude Auroral Boundaries during Two SubstormsGeotail plasma and field measurements at -95 R(sub E) are compared with extensive ground-based, near-Earth, and geosynchronous measurements to study relationships between auroral activity and magnetotail dynamics during the expansion phases of two substorms. The studied intervals are representative of intermittent, moderate activity. The behavior of the aurora and the observed effects at Geotail for both events are harmonized by the concept of the activation of near-Earth X lines (NEXL) after substorm onsets, with subsequent discharges of one or more plasmoids down the magnetotail. The plasmoids must be viewed as three-dimensional structures which are spatially limited in the dawn-dusk direction. Also, reconnection at the NEXL must proceed at variable rates on closed magnetic field lines for significant times before beginning to reconnect lobe flux. This implies that the plasma sheet in the near-Earth magnetotail is relatively thick in comparison with an embedded current sheet and that both the NEXL and distant X line can be active simultaneously. Until reconnection at the NEXL engages lobe flux, the distant X line maintains control of the poleward auroral boundary. If the NEXL remains active after reaching the lobe, the auroral boundary can move poleward explosively. The dynamics of high-latitude aurora in the midnight region thus provides a means for monitoring these processes and indicating when significant lobe flux reconnects at the NEXL.
Document ID
19970027652
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
External Source(s)
doi:10.1029/97JA00307
Authors
Maynard, N. C. (Mission Research Corp. Nashua, NH United States)
Burke, W. J. (Phillips Lab. Hanscom AFB, MA United States)
Erickson, G. M. (Boston Univ. Boston, MA United States)
Nakamura, M. (Tokyo Univ. Japan)
Mukai, T. (Tokyo Univ. Sagamihara, Japan)
Kokubun, S. (Nagoya Univ. Toyokawa, Japan)
Yamamoto, T. (Tokyo Univ. Kanagawa, Japan)
Jacobsen, B. (Oslo Univ. Norway)
Egeland, A. (Oslo Univ. Norway)
Samson, J. C. (Alberta Univ. Edmonton, Alberta Canada)
Weimer, D. R. (Mission Research Corp. Nashua, NH United States)
Reeves, G. D. (Los Alamos National Lab. NM United States)
Luhr, H. (Technische Univ. Brunswick, Germany)
Date Acquired
September 6, 2013
Publication Date
May 1, 1997
Publication Information
Publication: Journal of Geophysical Research
Publisher: American Geophysical Union
Volume: 102
Issue: A5
ISSN: 0148-0227
Subject Category
Geophysics
Report/Patent Number
Paper-97JA00307
NAS 1.26:205249
NASA-CR-205249
Accession Number
97N26574
Funding Number(s)
CONTRACT_GRANT: NSF ATM-94-01629
CONTRACT_GRANT: NAGw-2627
Distribution Limits
Public
Copyright
Public Use Permitted.

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