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| Titel |
Multi-satellite study of the excitation of Pc3 and Pc4-5 ULF waves and their penetration across the plasmapause during the 2003 Halloween superstorm |
| VerfasserIn |
G. Balasis, I. A. Daglis, I. R. Mann, C. Papadimitriou, E. Zesta, M. Georgiou, R. Haagmans, K. Tsinganos |
| 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 ; 33, no. 10 ; Nr. 33, no. 10 (2015-10-05), S.1237-1252 |
| Datensatznummer |
250121255
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| Publikation (Nr.) |
 copernicus.org/angeo-33-1237-2015.pdf |
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| Zusammenfassung |
| We use multi-satellite and ground-based magnetic data to investigate the
concurrent characteristics of Pc3 (22–100 mHz) and Pc4-5 (1–22 mHz)
ultra-low-frequency (ULF) waves on the 31 October 2003 during the Halloween
magnetic superstorm. ULF waves are seen in the Earth's magnetosphere, topside
ionosphere, and Earth's surface, enabling an examination of their propagation
characteristics. We employ a time–frequency analysis technique and examine
data from when the Cluster and CHAMP spacecraft were in good local time (LT)
conjunction near the dayside noon–midnight meridian. We find clear evidence
of the excitation of both Pc3 and Pc4-5 waves, but more significantly we find
a clear separation in the L shell of occurrence of the Pc4-5 and Pc3 waves in
the equatorial inner magnetosphere, separated by the density gradients at the
plasmapause boundary layer. A key finding of the wavelet spectral analysis of
data collected from the Geotail, Cluster, and CHAMP spacecraft and the
CARISMA and GIMA magnetometer networks was a remarkably clear transition of
the waves' frequency into dominance in a higher-frequency regime within the
Pc3 range. Analysis of the local field line resonance frequency suggests that
the separation of the Pc4-5 and Pc3 emissions across the plasmapause is
consistent with the structure of the inhomogeneous field line resonance
Alfvén continuum. The Pc4-5 waves are consistent with direct excitation by
the solar wind in the plasma trough, as well as Pc3 wave absorption in the
plasmasphere following excitation by upstream waves originating at the bow
shock in the local noon sector. However, despite good solar wind coverage, our
study was not able to unambiguously identify a clear explanation for the
sharp universal time (UT) onset of the discrete frequency and large-amplitude
Pc3 wave power. |
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