INVESTIGATION OF THE INFLUENCE OF SOLAR ACTIVITY ON TOTAL ELECTRON CONTENT (TEC) AT THE KOUDOUGOU STATION DURING RECURRENT GEOMAGNETIC ACTIVITY DURING SOLAR CYCLE 24: A DETAILED ANALYSIS

The objective of this article is to examine the dependence of total electron content (TEC) on solar activity parameters such as the sunspot number (SN) index, the F10.7 solar radio flux and the EUV flux. Daily, monthly and annual average TEC data, as well as solar indices, were used for the study. TEC observations were made in Koudougou (12 15 N; -2 20E), Burkina Faso, using a dual-frequency GPS receiver. The working period covers the years 2010 to 2017, focusing on recurring geomagnetic days. To model the variation in TEC as a function of solar parameters, a quadratic fit was used as a model to describe the daily, monthly and annual variation in TEC. Linear and non-linear coefficients were calculated to understand the trends in the variation. The results show that the variation in TEC corresponds well to the trend in solar parameters for most of the days observed during the study period. Maximum TEC values were recorded at the equinoxes, while minimum values were observed at the solstices. Other parameters will therefore need to be taken into account to explain this difference. In addition, the variation in TEC as a function of EUV showed relatively small deviations from the variation due to F10.7 flux and SN. This suggests that EUV may be more appropriate for modelling solar variation in TEC, particularly for long-term trends. Finally, although the linear trend in solar variations in TEC was frequently observed, significant saturation and amplification trends were also noted across the months and years analysed. This complexity in the solar variation of TEC highlights the need for further studies to understand the effect of solar parameters on TEC.