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| Titel |
Excitation of transient lobe cell convection and auroral arc at the cusp poleward boundary during a transition of the interplanetary magnetic field from south to north |
| VerfasserIn |
P. E. Sandholt, C. J. Farrugia, S. W. H. Cowley, Mark Lester, J.-C. Cerisier |
| 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 ; 19, no. 5 ; Nr. 19, no. 5, S.487-493 |
| Datensatznummer |
250014249
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| Publikation (Nr.) |
 copernicus.org/angeo-19-487-2001.pdf |
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| Zusammenfassung |
We document the activation
of transient polar arcs emanating from the cusp within a 15 min long
intermediate phase during the transition from a standard two-cell convection
pattern, representative of a strongly southward interplanetary magnetic field (IMF),
to a "reverse" two-cell pattern, representative of strongly northward
IMF conditions. During the 2–3 min lifetime of the arc, its base in the cusp,
appearing as a bright spot, moved eastward toward noon by ~ 300 km. As the arc
moved, it left in its "wake" enhanced cusp precipitation. The polar
arc is a tracer of the activation of a lobe convection cell with clockwise
vorticity, intruding into the previously established large-scale distorted
two-cell pattern, due to an episode of localized lobe reconnection. The lobe
cell gives rise to strong flow shear (converging electric field) and an
associated sheet of outflowing field-aligned current, which is manifested by the
polar arc. The enhanced cusp precipitation represents, in our view, the
ionospheric footprint of the lobe reconnection process.
Key words. Magnetospheric physics (auroral
phenomena; magnetopause, cusp, and boundary layers; plasma convection) |
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