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| Titel |
Global properties of magnetotail current sheet flapping: THEMIS perspectives |
| VerfasserIn |
A. Runov, V. Angelopoulos, V. A. Sergeev, K.-H. Glassmeier, U. Auster, J. McFadden, D. Larson, I. Mann |
| 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 ; 27, no. 1 ; Nr. 27, no. 1 (2009-01-19), S.319-328 |
| Datensatznummer |
250016373
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| Publikation (Nr.) |
 copernicus.org/angeo-27-319-2009.pdf |
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| Zusammenfassung |
| A sequence of magnetic field oscillations with an amplitude of up to 30 nT
and a time scale of 30 min was detected by four of the five THEMIS spacecraft
in the magnetotail plasma sheet. The probes P1 and P2 were at X=−15.2 and
−12.7 RE and P3 and P4 were at X=−7.9 RE. All four probes were at
−6.5>Y>−7.5 RE (major conjunction). Multi-point timing analysis of the
magnetic field variations shows that fronts of the oscillations propagated
flankward (dawnward and Earthward) nearly perpendicular to the direction of
the magnetic maximum variation (B1) at velocities of 20–30 km/s. These
are typical characteristics of current sheet flapping motion. The observed
anti-correlation between ∂B1/∂t and the Z-component of
the bulk velocity make it possible to estimate a flapping amplitude of 1 to
3 RE. The cross-tail scale wave-length was found to be about 5 RE.
Thus the flapping waves are steep tail-aligned structures with a lengthwise
scale of >10 RE. The intermittent plasma motion with the cross-tail
velocity component changing its sign, observed during flapping, indicates
that the flapping waves were propagating through the ambient plasma.
Simultaneous observations of the magnetic field variations by THEMIS
ground-based magnetometers show that the flapping oscillations were observed
during the growth phase of a substorm. |
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