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| Titel |
The influence of IMF By on the nature of the nightside high-latitude ionospheric flow during intervals of positive IMF Bz |
| VerfasserIn |
A. Grocott, S. V. Badman, S. W. H. Cowley, T. K. Yeoman, P. J. Cripps |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 22, no. 5 ; Nr. 22, no. 5 (2004-04-08), S.1755-1764 |
| Datensatznummer |
250014874
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| Publikation (Nr.) |
 copernicus.org/angeo-22-1755-2004.pdf |
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| Zusammenfassung |
This paper further addresses the issue of nightside flow bursts which occur
during intervals of northward but strongly BY-influenced IMF. Recent
discussions of such bursts concerned intervals during which the IMF BY
component was negative. The present study concerns an interval of
BY-positive IMF which occurred on 20 March 2002 (01:00-12:00UT).
During the interval BY increased steadily from ~2 to 12nT,
whilst the BZ component decreased steadily from ~10 to 0nT.
There was thus a ~6-h sub-interval during which the IMF clock angle
remained between 30° and 60°, such that moderate dayside
reconnection and open flux production was maintained. It is found that flow
bursts of a similar size and speed to those observed under BY negative
(~1000m s-1, spanning 2-3h of MLT in the
midnight sector) also occur when BY is positive. However, the direction
of east-west flow is reversed, indicating that they are driven by processes
in the magnetosphere which are directly related to the orientation of the
IMF. It is suggested that they are caused by a reconfiguration of an
asymmetric tail resulting from prolonged dayside reconnection with a
BY-dominated IMF. This is consistent with previous suggestions that
they are associated with convective transport following reconnection in the
more distant tail. Analysis of ground magnetic data, auroral images and
geosynchronous particle data also show associated features, but indicate
that the flow bursts are not directly associated with substorms.
Key words. Ionosphere (plasma convection; ionospheremagnetosphere
interactions) – Magnetospheric Physics
(magnetotail) |
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