Seasonal Assessment of IRI-2016, IRI-2020, and AfriTEC Models Applicability in East Africa During Ascending phase of Solar Cycle 25

Reliable estimation of ionospheric Total Electron Content (TEC) is important for optimizing satellite based communication and navigation systems. This study evaluates the performance of regional and global ionospheric models IRI-2016, IRI-2020, and AfriTEC in capturing TEC variations over East Africa during the ascending phase of Solar Cycle 25 (2021-2022). Model outputs were compared against Vertical TEC (VTEC) measurements from selected International GNSS Service (IGS) stations, with seasonal variability represented by four characteristic seasons corresponding to the March equinox, June solstice, September equinox, and December solstice. Analyses were conducted over the full two year period. Model accuracy was assessed using Root Mean Square Error (RMSE) and Pearson correlation coefficients, complemented by histogram analysis of residuals to examine bias polarity and error distribution. Results reveal that AfriTEC errors are generally centered near zero during equinox periods, indicating balanced model performance. However, during solstice periods particularly in December errors exhibit broader distributions and a negative bias, indicating consistent underestimation of TEC. The model also tends to underestimate peak TEC values and struggles to fully capture storm driven ionospheric irregularities. These findings highlight AfriTEC’s effectiveness as a reliable quiet time ionospheric model for East Africa, while underscoring the need for enhanced storm time parameterizations and the integration of higher resolution, real time geophysical inputs. Such improvements are essential for advancing the accuracy of ionospheric models to better support space weather monitoring and GNSS-based applications across the African region.