Study of the Physical Parameters of the Ionosphere Over Nigeria Using GPS-TEC Data

The ionosphere significantly affects the propagation of radio waves used in satellite navigation, HF communication, and remote sensing systems. Nigeria's equatorial location places it within the equatorial ionisation anomaly region, where strong ionospheric variability poses challenges for GPS navigation accuracy and satellite communication reliability. This study characterises key physical parameters of the ionosphere over Nigeria including total electron content, ionospheric scintillation index S4, and TEC depletion events associated with equatorial plasma bubbles, using GPS receiver data from six dual-frequency geodetic stations of the Nigerian GNSS Reference Network. TEC is derived from differential GPS phase and code measurements and corrected for satellite and receiver differential biases. Data from 2020 to 2023 are analysed for seasonal and diurnal patterns. Results indicate peak TEC values of 40 to 80 TECU between 14:00 and 16:00 local time during the equinoctial months of March and September. S4 scintillation indices exceeding 0.3 are observed during post-sunset hours, primarily from March to April and September to November. The study provides ionospheric characterisation data for improving GPS error correction models over the Nigerian region. Keywords: ionosphere, total electron content, GPS-TEC, Nigeria, equatorial plasma bubble