Studies of Total Electron Content variations at low-latitude stations within the Equatorial Ionization Anomaly zone

The total electron content (TEC) is an important parameter to monitor for possible space weather impacts. The radio waves that pass through the earth’s ionosphere travel more slowly than their free space velocity due to group path delay of the ionosphere. This group path delay is directly proportional to the TEC of the ionosphere. Using dual frequency GPS receiver at low latitude stations of Ile-Ife (7.52 o N, 4.28 o E), Addis Ababa (9.04 o N, 38.77 o E) and Bangalore (13.03 o E, 77.57 o E), all located within 0 15 o N of the equatorial anomaly region, the measurement of ionospheric TEC for 2012 has been carried out. The data from the three stations were used to study the diurnal, monthly and seasonal variations of TEC. The diurnal variations maximize between 10:00 – 16:00UT, 08:00 – 14:00UT and 06:00 – 12:00UT for Ile-Ife, Addis Ababa and Bangalore stations respectively. The diurnal variations showed wave-like pertubation during disturbed and quiet periods at Bangalore and Addis Ababa stations. The monthly average TEC variations showed that the month of March recorded the highest TEC value of ~59TECu at about 16:00UT in Ile-Ife station, while TEC at Addis Ababa and Bangalore maximize in October with ~72TECu and 65TECu at about 11:00UT and 09:00UT respectively. Seasonal variations showed that TEC maximizes during the equinoctial months and least in summer, over the three stations. Geomagnetic storms enhance TEC variations in the three stations.

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