Solar Activity Effects on Total Electron Content Variations at Low-Latitude Stations

The dual frequency signals from the GPS satellites recorded at Ile-Ife, Nigeria (Geomagnetic Lat 7.52^oN and Long 4.28^oE); Addis Ababa, Ethiopia (Geomagnetic Lat 9.04^oN, Long 38.77^oE) and Bangalore, India (Geomagnetic Lat13.03^oE, Long 77.57 ^oE) have been analysed to study the effects of solar activities on Total Electron Content (TEC). The variations of TEC at maximum and minimum solar radio flux (F10.7) and sunspot number (SSN) for the two years revealed that the magnitude of TEC are influenced by solar activity, with maximum solar indices corresponding to maximum TEC values and was dependent on season and geographic location. The best correlation was found between TEC and F10.7, with a highest value of 0.851 at Addis Ababa in 2011.The statistical analysis revealed that in 2011, the daily mean peak TEC increases by 0.298, 0.550 and 0.531 TECu with each additional SFU of F10.7 in Ile-Ife, Addis Ababa and Bangalore respectively. The coefficient of determination values of 48.7%, 72.4% and 70.6% in the three stations indicates the level of variance in TEC due to F10.7. The standard deviation values of 7.514, 8.189 and 8.875 for Ile-Ife, Addis Ababa and Bangalore respectively for F10.7 shows that Ile-Ife had the best of its values concentrated around the mean while Bangalore had the least.

Keywords: Low latitude Ionosphere, Equatorial Ionisation Anomaly, Total Electron Content, Solar activity.