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| Titel |
Flux closure during magnetotail reconnection |
| VerfasserIn |
Kristian Snekvik, Eija Tanskanen, Nikolai Østgaard |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250052585
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| Zusammenfassung |
| The ability to store magnetic energy from the solar wind, for later release, is a crucial part of
magnetotail dynamics. Under which conditions is the magnetotail able to store energy, and
how do the subsequent release of energy influence the dynamics in the tail? To
address these questions, we have studied 13 reconnection event with in-situ Cluster
observations from the current sheet and the reconnection region at about 19Â RE
from the Earth. We find that reconnection usually occurs after a period of gradual
current sheet thinning. The thickness decreases from 23000 km to 10000 km in
about 50 minutes, on average. This thinning occurs whether or not there is a total
pressure increase or a current sheet stretching in the same time interval. The lobe
magnetic field, at reconnection onset, is very variable and highly dependent on solar
wind parameters, but after unloading it decreases to a more stable value of about
22Â nT. The observations indicate that reconnection does not occur when the lobe
magnetic field is below this value. It has been estimated that the effective length of
the nightside X-line must be about 30Â RE to accommodate the necessary flux
transport in the tail. If this involves one or several X-lines, remains to be found. |
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