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| Titel |
Cluster PEACE observations of electrons during magnetospheric flux transfer events |
| VerfasserIn |
C. J. Owen, A. N. Fazakerley, P. J. Carter, A. J. Coates, I. C. Krauklis, S. Szita, M. G. G. T. Taylor, P. Travnicek, G. Watson, R. J. Wilson, A. Balogh, M. W. Dunlop |
| 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. 10/12 ; Nr. 19, no. 10/12, S.1509-1522 |
| Datensatznummer |
250014131
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| Publikation (Nr.) |
 copernicus.org/angeo-19-1509-2001.pdf |
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| Zusammenfassung |
During the first quarter
of 2001 the apogees of the Cluster spacecraft quartet precessed through midday
local times. This provides the first opportunity for 4 spacecraft studies of
the bow shock, magnetosheath and the dayside magnetopause current layer and
boundary layers. In this paper, we present observations of electrons in the
energy range ~ 10 eV–26 keV made by the Plasma Electron And Current
Experiment (PEACE) located just inside the magnetopause boundary, together with
supporting observations by the Flux Gate Magnetometer (FGM). During these
observations, the spacecraft have separations of ~ 600 km. This scale size is
of the order or less than the typical size of flux transfer events (FTEs),
which are expected to be observed following bursts of reconnection on the
dayside magnetopause. We study, in detail, the 3-D configuration of electron
populations observed around a series of enhancements of magnetosheath-like
electrons which were observed within the magnetosphere on 2 February 2001. We
find that individual spacecraft observe magnetic field and electron signatures
that are consistent with previous observations of magnetospheric FTEs. However,
the differences in the signatures between spacecraft indicate that these FTEs
have substructure on the scale of the spacecraft separation. We use these
differences and the timings of the 4 spacecraft observations to infer the
motions of the electron populations and thus the configuration of these
substructures. We find that these FTEs are moving from noon towards dusk. The
inferred size and speed of motion across the magnetopause, in one example, is ~
0.8 RE and ~ 70 km s-1 respectively. In addition,
we observe a delay in and an extended duration of the signature at the
spacecraft furthest from the magnetopause. We discuss the implications of these
4 spacecraft observations for the structure of these FTEs. We suggest that
these may include a compression of the closed flux tubes ahead of the FTE,
which causes density and field strength enhancements; a circulation of open
flux tubes within the FTE itself, which accounts for the delay in the arrival
of the magnetosheath electron populations at locations deepest within the
magnetosphere; and a possible trapping of magnetospheric electrons on the most
recently opened flux tubes within the FTE.
Key words. Magnetospheric physics
(magnetopause, cusp and boundary layers; solar wind - magnetosphere
interactions) |
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