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Titel |
Storm-time longitudinally propagating asymmetric modes at low latitudes |
VerfasserIn |
A. K. Singh, A. K. Sinha, R. Rajaram, B. M. Pathan |
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. 1 ; Nr. 30, no. 1 (2012-01-13), S.131-141 |
Datensatznummer |
250017169
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Publikation (Nr.) |
copernicus.org/angeo-30-131-2012.pdf |
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Zusammenfassung |
The westward flowing toroidal ring current at about 2–7 RE in the Earth's
equatorial plane consists of symmetric and asymmetric parts. Zonal mean of
H disturbances from longitudinally distributed low latitude stations
represents the symmetric contribution, whereas departure from the zonal mean
gives local time dependent asymmetric component at each of the stations.
Through a standard analysis of closely spaced low latitude geomagnetic data
we demonstrate 24 h periodicity in the asymmetric component of the
storm-time ring current, which is related to the changing local time due to
rotation of the Earth. Detailed examination of shorter period oscillations,
when observed globally, often show westward propagating modes. Eastward
propagating mode was also observed in one case. Based on satellite and radar
observations covering a narrow longitude region, westward and eastward
propagating modes had been reported in earlier studies. In this study, we
report that similar propagating modes which are available on global scale,
can be identified using ground-based magnetometer data. These globally
propagating modes, observed from ground-based studies, find obvious practical
application in diagnostics of the magnetosphere, especially the ring current
region. Simultaneous use of satellite and ground-based data should establish
the morphology of such modes. |
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