Investigation of Ionospheric Scintillation Effects on GPS Signal Quality Over the Nigerian Equatorial Region

Background: Nigeria lies within the equatorial ionospheric anomaly belt where plasma irregularities cause severe GPS signal scintillation, degrading positioning accuracy for navigation, agriculture, and land surveying applications. Systematic characterisation of scintillation at multiple Nigerian locations fills a critical observational gap. Aim: This study investigated ionospheric scintillation effects on GPS signal quality at five stations distributed across Nigeria's geopolitical zones. Methods: GPS scintillation receivers were operated at stations in Lagos, Abuja, Kano, Enugu, and Maiduguri over 18 months, recording the S4 amplitude scintillation index and phase scintillation index at 50 Hz sampling rate. Scintillation events were correlated with ionospheric total electron content from GNSS receivers and solar flux indices. Results: Severe scintillation events (S4 > 0.6) occurred predominantly between 20:00 and 02:00 local time in all seasons, with peak occurrence from September to November. Southern stations experienced 2.3 times more severe events than northern stations. Positioning errors during severe scintillation exceeded 15 metres in 12% of affected epochs. Conclusion: Equatorial ionospheric scintillation causes significant positioning degradation across Nigeria with strong seasonal and diurnal patterns. The established scintillation climatology supports improved GPS receiver error modelling and user advisory services for affected applications. Keywords: ionospheric scintillation, GPS, equatorial ionosphere, Nigeria, positioning accuracy.