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| Titel |
Equatorial plasma bubbles in the ionosphere over Eritrea: occurrence and drift speed |
| VerfasserIn |
R. H. Wiens, B. M. Ledvina, P. M. Kintner, M. Afewerki, Z. Mulugheta |
| 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 ; 24, no. 5 ; Nr. 24, no. 5 (2006-07-03), S.1443-1453 |
| Datensatznummer |
250015560
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| Publikation (Nr.) |
 copernicus.org/angeo-24-1443-2006.pdf |
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| Zusammenfassung |
| An all-sky imager was installed in Asmara, Eritrea (15.4° N,
38.9° E, 7° N dip) and used to monitor the OI 630-nm
nightglow. Nine months of data were studied between September 2001
and May 2002, a time including the recent maximum in the solar
activity cycle. Equatorial plasma bubbles (EPBs) were recorded on
63% of nights with adequate viewing conditions. The station
location within view of the equatorial ionization anomaly and with
a magnetic declination near zero makes it an excellent test case
for comparison with satellite studies of the seasonal variation of EPBs with longitude.
The imager was accompanied by two
Cornell GPS scintillation monitors, and the amplitude
scintillation data are compared to the all-sky data. GPS
scintillations indicate the beginning of EPBs, but die out sooner
in the post-midnight period than the larger scale EPBs. Both
phenomena exhibit clear occurrence maxima around the equinoxes.
Ionospheric zonal drift speeds have been deduced from EPB and GPS
scintillation pattern movement. Average near-midnight EPB drift
speeds are between 100 and 120 m/s most months, with the GPS
scintillation speeds being about the same. A winter drift speed
maximum is evident in both EPB and GPS scintillation monthly
means. |
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