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| Titel |
ULF geomagnetic pulsations at different latitudes in Antarctica |
| VerfasserIn |
P. Francia, M. Lauretis, M. Vellante, U. Villante, A. Piancatelli |
| 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. 9 ; Nr. 27, no. 9 (2009-09-29), S.3621-3629 |
| Datensatznummer |
250016656
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| Publikation (Nr.) |
 copernicus.org/angeo-27-3621-2009.pdf |
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| Zusammenfassung |
| We present a study aimed to characterize the ULF (1–100 mHz) geomagnetic
pulsation activity in the polar cap at different latitudes. We used magnetic
measurements obtained through 2005–2007 in Antarctica, at Dome C (89° S
corrected geomagnetic latitude) and at Terra Nova Bay (80° S corrected
geomagnetic latitude). The results indicate a solar wind control of the wave
activity, more important at larger distances from the cusp, as well as a
significant role of the local ionospheric conditions. The different position
of the two stations, with respect to the cusp and closed field lines, is
responsible for the observed different pulsation characteristics. At Terra
Nova Bay, due to the approaching of the station to the cusp and closed field
lines in the daytime, the ULF power is characterized by a maximum around
noon; daytime pulsation events in the Pc5 frequency band are related to the
fundamental field line resonances occurring at lower latitudes, while higher
harmonics of the fundamental may account for the characteristics of Pc3–4
pulsations. In the nighttime, at Pc3 frequencies, the results suggest waves
propagating sunward, possibly due to the transmission of upstream waves from
the magnetosheath via the magnetotail lobes. At Dome C, near the geomagnetic
pole and very far from closed field lines, the ULF power in any frequency
band only shows an enhancement in the postmidnight sector, more pronounced
for Pc3 pulsations. The ULF activity appears to be driven by processes
occurring in the magnetotail: in particular, nighttime Pc3 pulsation events
may be originated from upstream wave penetration through the magnetotail
lobes. |
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