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| Titel |
Multi-instrument observations of the ionospheric counterpart of a bursty bulk flow in the near-Earth plasma sheet |
| VerfasserIn |
A. Grocott, T. K. Yeoman, R. Nakamura, S. W. H. Cowley, H. U. Frey, H. Rème, B. Klecker |
| 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. 4 ; Nr. 22, no. 4 (2004-04-02), S.1061-1075 |
| Datensatznummer |
250014823
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| Publikation (Nr.) |
 copernicus.org/angeo-22-1061-2004.pdf |
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| Zusammenfassung |
On 07 September 2001 the Cluster spacecraft observed a "bursty bulk flow" event in the
near-Earth central plasma sheet. This paper presents a detailed study of the coincident
ground-based observations and attempts to place them within a simple physical framework. The event in
question occurs at ~22:30 UT, some 10min after a southward turning of the IMF. IMAGE and
SAMNET magnetometer measurements of the ground magnetic field reveal perturbations of a few
tens of nT and small amplitude Pi2 pulsations. CUTLASS radar observations of ionospheric
plasma convection show enhanced flows out of the polar cap near midnight, accompanied by an
elevated transpolar voltage. Optical data from the IMAGE satellite also show that there is a
transient, localised ~1 kR brightening in the UV aurora. These observations are consistent with the
earthward transport of plasma in the tail, but also indicate the absence of a typical
"large-scale" substorm current wedge. An analysis of the field-aligned current system implied by the radar
measurements does suggest the existence of a small-scale current "wedgelet", but one which lacks
the global scale and high conductivities observed during substorm expansions.
Key words. Ionosphere (auroral ionosphere; ionospheremagnetosphere
interactions; plasma convection) |
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