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| Titel |
Geometry of duskside equatorial current during magnetic storm main phase as deduced from magnetospheric and low-altitude observations |
| VerfasserIn |
S. Dubyagin, N. Ganushkina, S. Apatenkov, M. Kubyshkina, H. Singer, M. Liemohn |
| 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 ; 31, no. 3 ; Nr. 31, no. 3 (2013-03-04), S.395-408 |
| Datensatznummer |
250019001
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| Publikation (Nr.) |
 copernicus.org/angeo-31-395-2013.pdf |
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| Zusammenfassung |
| We present the results of a coordinated study of the moderate
magnetic storm on 22 July 2009. The THEMIS and GOES observations
of magnetic field in the inner magnetosphere were complemented by
energetic particle observations at low altitude by the six NOAA
POES satellites. Observations in the vicinity of geosynchronous
orbit revealed a relatively thin (half-thickness of less than 1 RE)
and intense current sheet in the dusk MLT sector during the
main phase of the storm. The total westward current (integrated
along the z-direction) on the duskside at r ~ 6.6 RE was
comparable to that in the midnight sector. Such a configuration
cannot be adequately described by existing magnetic field models
with predefined current systems (error in B > 60 nT). At the same
time, low-altitude isotropic boundaries (IB) of > 80 keV protons
in the dusk sector were shifted ~ 4° equatorward relative
to the IBs in the midnight sector. Both the equatorward IB shift
and the current strength on the duskside correlate with the
Sym-H* index. These findings imply a close relation between
the current intensification and equatorward IB shift in the dusk
sector. The analysis of IB dispersion revealed that high-energy
IBs (E > 100 keV) always exhibit normal dispersion (i.e., that for
pitch angle scattering on curved field lines). Anomalous
dispersion is sometimes observed in the low-energy channels
(~ 30–100 keV). The maximum occurrence rate of anomalous
dispersion was observed during the main phase of the storm in the
dusk sector. |
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