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| Titel |
On the location of dayside magnetic reconnection during an interval of duskward oriented IMF |
| VerfasserIn |
J. A. Wild, S. E. Milan, J. A. Davies, M. W. Dunlop, D. M. Wright, C. M. Carr, A. Balogh, H. Rème, A. N. Fazakerley, A. Marchaudon |
| 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 ; 25, no. 1 ; Nr. 25, no. 1 (2007-02-01), S.219-238 |
| Datensatznummer |
250015773
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| Publikation (Nr.) |
 copernicus.org/angeo-25-219-2007.pdf |
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| Zusammenfassung |
| We present space- and ground-based observations of the signatures of magnetic
reconnection during an interval of duskward-oriented interplanetary magnetic
field on 25 March 2004. In situ field and plasma measurements are drawn from
the Double Star and Cluster satellites during traversals of the pre-noon
sector dayside magnetopause at low and high latitudes, respectively. These
reveal the typical signatures of flux transfer events (FTEs), namely bipolar
perturbations in the magnetic field component normal to the local
magnetopause, enhancements in the local magnetic field strength and mixing of
magnetospheric and magnetosheath plasmas. Further evidence of magnetic
reconnection is inferred from the ground-based signatures of pulsed
ionospheric flow observed over an extended interval. In order to ascertain
the location of the reconnection site responsible for the FTEs, a simple
model of open flux tube motion over the surface of the magnetopause is
employed. A comparison of the modelled and observed motion of open flux tubes
(i.e. FTEs) and plasma flow in the magnetopause boundary layer indicates that
the FTEs observed at both low and high latitudes were consistence with the
existence of a tilted X-line passing through the sub-solar region, as
suggested by the component reconnection paradigm. While a high latitude
X-line (as predicted by the anti-parallel description of reconnection) may
have been present, we find it unlikely that it could have been responsible
for the FTEs observed in the pre-noon sector under the observed IMF
conditions. Finally, we note that throughout the interval, the magnetosphere
was bathed in ULF oscillations within the solar wind electric field. While no
one-to-one correspondence with the pulsed reconnection rate suggested by the
ground-based observation of pulsed ionospheric flow has been demonstrated, we
note that similar periodicity oscillations were observed throughout the solar
wind-magnetosphere-ionosphere system. These findings are consistent with
previously proposed mechanisms of solar wind modulation of the dayside
reconnection rate. |
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