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| Titel |
Overlapping ion structures in the mid-altitude cusp under northward IMF: signature of dual lobe reconnection? |
| VerfasserIn |
F. Pitout, C. P. Escoubet, M. G. G. T. Taylor, J. Berchem, A. P. Walsh |
| 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 ; 30, no. 3 ; Nr. 30, no. 3 (2012-03-06), S.489-501 |
| Datensatznummer |
250017195
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| Publikation (Nr.) |
 copernicus.org/angeo-30-489-2012.pdf |
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| Zusammenfassung |
| On some rare occasions, data from the Cluster Ion
Spectrometer (CIS) in the mid-altitude cusp reveal overlapping ion
populations under northward interplanetary magnetic field (IMF). While the
poleward part of the cusp exhibits the expected reverse dispersion due to
lobe reconnection, its equatorward part shows a second ion population at
higher-energy that coexists with the low energy tail of the dispersion. This
second population is either dispersionless or slightly dispersed with
energies increasing with increasing latitudes, indicative of lobe
reconnection as well. Our analysis of a case that occurred 3 September 2002
when the IMF stayed northward for more than two hours suggests that the
second population comes from the opposite hemisphere and is very likely on
newly-closed field lines. We interpret this overlap of cusp populations as a
clear mid-altitude signature of re-closed magnetic field lines by double
lobe reconnection (reconnection in both hemispheres) under northward IMF.
This interpretation is supported by modelling performed with the Cooling
model and an MHD model. |
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