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| Titel |
Equatorial plasma bubbles and L-band scintillations in Africa during solar minimum |
| VerfasserIn |
V. V. Paznukhov, C. S. Carrano, P. H. Doherty, K. M. Groves, R. G. Caton, C. E. Valladares, G. K. Seemala, C. T. Bridgwood, J. Adeniyi, L. L. N. Amaeshi, B. Damtie, F. D'Ujanga Mutonyi, J. O. H. Ndeda, P. Baki, O. K. Obrou, B. Okere, G. M. Tsidu |
| 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. 4 ; Nr. 30, no. 4 (2012-04-16), S.675-682 |
| Datensatznummer |
250017211
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| Publikation (Nr.) |
 copernicus.org/angeo-30-675-2012.pdf |
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| Zusammenfassung |
We report on the longitudinal, local time and seasonal occurrence of
equatorial plasma bubbles (EPBs) and L band (GPS) scintillations over
equatorial Africa. The measurements were made in 2010, as a first step
toward establishing the climatology of ionospheric irregularities over
Africa. The scintillation intensity is obtained by measuring the standard
deviation of normalized GPS signal power. The EPBs are detected using an
automated technique, where spectral analysis is used to extract and identify
EPB events from the GPS TEC measurements.
Overall, the observed seasonal climatology of the EPBs as well as GPS
scintillations in equatorial Africa is adequately explained by geometric
arguments, i.e., by the alignment of the solar terminator and local
geomagnetic field, or STBA hypothesis (Tsunoda, 1985, 2010a). While
plasma bubbles and scintillations are primarily observed during equinoctial
periods, there are longitudinal differences in their seasonal occurrence
statistics. The Atlantic sector has the most intense, longest lasting, and
highest scintillation occurrence rate in-season. There is also a pronounced
increase in the EPB occurrence rate during the June solstice moving west to
east. In Africa, the seasonal occurrence shifts towards boreal summer
solstice, with fewer occurrences and shorter durations in equinox seasons.
Our results also suggest that the occurrence of plasma bubbles and GPS
scintillations over Africa are well correlated, with scintillation intensity
depending on depletion depth. A question remains about the possible physical
mechanisms responsible for the difference in the occurrence phenomenology of
EPBs and GPS scintillations between different regions in equatorial Africa. |
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