Variability of GPS-derived ionospheric TEC over Nigeria during a year of low solar activity

Abstract

An investigation of the diurnal and seasonal variability of ionospheric total electron content (TEC) over Nigeria is carried out in this study using the global positioning system (GPS) observable. Nigeria coordinates fall within the trough of the equatorial ionisation anomaly region of the African sector. The TEC data used were obtained from the ground-based GPS receiver stations of the Nigerian GNSS network of stations (NIGNET). The stations with their respective geomagnetic latitudes are: Abuja (–1.64°), Yola (–1.32°), Zaria (–0.13°), Kebbi (0.72°). The results of the diurnal analysis of the relative variability index (VD) revealed higher nighttime values than daytime values. The diurnal variation of VD also showed two conspicuous peaks: post-midnight and post-sunset. The diurnal–seasonal variation does not reveal any consistent pattern (no particular season leads the others throughout). On average, considering all the seasons together, maximum TEC variability occurred in Zaria (62%) and minimum in Yola (54%). Seasonally, maximum VD was recorded during the March equinox and the lowest was recorded during the December equinox.