Equatorial plasma bubbles and L-band scintillations in Africa during solar minimum

Journal article

Authors / Editors

Tsidu, Gizaw

Research Areas

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Publication Details

Author list: Paznukhov VV, Carrano CS, Doherty PH, Groves KM, Caton RG, Valladares CE, Seemala GK, Bridgwood CT, Adeniyi J, Amaeshi LLN, Damtie B, Mutonyi FD, Ndeda JOH, Baki P, Obrou OK, Okere B, Tsidu GM

Publisher: Copernicus Publications

Place: GOTTINGEN

Publication year: 2012

Journal: Annales Geophysicae (0992-7689)

Journal acronym: ANN GEOPHYS-GERMANY

Volume number: 30

Issue number: 4

Start page: 675

End page: 682

Number of pages: 8

ISSN: 0992-7689

eISSN: 1432-0576

Languages: English-Great Britain (EN-GB)

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Abstract

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.

Keywords

Equatorial ionosphere, Ionosphere, Ionospheric irregularities, Radio science, Space and satellite communication

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