Variations of Crest-to-Trough TEC Ratio of the East African Equatorial Anomaly Region
International Journal of Astrophysics and Space Science
Volume 4, Issue 1, February 2016, Pages: 12-20
Received: Dec. 21, 2015; Accepted: Dec. 29, 2015; Published: Mar. 2, 2016
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Bosco Oryema, Department of Physics, Busitema University, Tororo, Uganda
Edward Jurua, Department of Physics, Mbarara University of Science and Technology, Mbarara, Uganda
Nicolausi Ssebiyonga, Department of Physics, Makerere University, Kampala, Uganda
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In this paper, Vertical Total Electron Content (VTEC) data derived from dual-frequency GPS measurements obtained at two ground stations were used to study the variability of the equatorial ionization anomaly (EIA). The present study only focuses on analysis of the crest-to-trough TEC ratio (TEC-CTR) in the southern crest region. Data used in this study was obtained for the high solar activity year 2012. MAL2 station (Geomag Lat. -12.4°S, Geomag Long. 111.9°E) was considered for the southern crest region whereas ADIS station (Geomag Lat. 0.2°N, Geomag Long. 110.5°E) was considered for the trough region. Diurnal and seasonal variations as well as the dependency of TEC-CTR on solar activity levels were investigated in the present study. The results showed that the diurnal variation pattern of TEC-CTR is characterized by two remarkable peak values, one occurring in the post‐midnight hours around 02: 00-03: 00 UT (05: 00-06: 00 LT) and the second (highest) peak occurred in the post-sunset hours around 18: 00-20: 00 UT (21: 00-23: 00 LT). Seasonal TEC-CTR variations showed a semi-annual variation pattern, with maximum peak values occurring in the equinoctial months. TEC-CTR also revealed an existence of winter anomaly in this region, with higher values of TEC-CTR in the winter solstice than summer solstice. TEC-CTR in the daytime post-noon hours; between 01: 00-04: 00 UT (04: 00-07: 00 LT) does not vary much with the solar activity; however, TEC-CTR in the post-sunset hours; between 16: 00-20: 00 UT (19: 00-23: 00 LT) shows a clear dependence on the solar activity, with its values increasing with solar activity.
Total Electron Content (TEC), Equatorial Ionization Anomaly (EIA), GPS Measurements, Solar Activity
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Bosco Oryema, Edward Jurua, Nicolausi Ssebiyonga, Variations of Crest-to-Trough TEC Ratio of the East African Equatorial Anomaly Region, International Journal of Astrophysics and Space Science. Vol. 4, No. 1, 2016, pp. 12-20. doi: 10.11648/j.ijass.20160401.12
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