Validation of NeQuick-2 Model for foE prediction at Ouagadougou Under Geomagnetically Quiet Conditions

Abstract. This study evaluates the performance of the NeQuick-2 model in simulating foE and capturing its variability under geomagnetically quiet conditions at Ouagadougou (latitude 12.4° N; longitude 358.5° E; magnetic dip 1.45° N), considering diurnal, seasonal, and solar-activity effects. The Ouagadougou station falls within the trough belt of the equatorial ionization anomaly region in West Africa. The analysis was carried out during the solar minimum and solar maximum phases of Solar Cycles 21 and 22.

Comparisons between NeQuick-2 predictions and ionosonde observations show that the model successfully reproduces the overall diurnal morphology of foE across all seasons and solar activity phases. However, systematic discrepancies are observed mainly at sunrise (transition between nighttime and daytime) and sunset (transition between daytime and nighttime) periods (06:00 LT and 18:00–19:00 LT), as well as during the equinoctial seasons, when the model frequently underestimates the observed values, particularly around the daytime maximum. These limitations are more pronounced during periods of low solar activity.

Statistical analysis based on the root mean square error (RMSE) and the coefficient of determination (R²) reveals a significant improvement in the performance of NeQuick-2 during the solar maximum phases of both solar cycles. The best agreement between model predictions and observations is generally obtained during winter and summer, whereas the poorest performance occurs during spring and autumn. This agreement is particularly evident during Solar Cycle 22, for which the coefficients of determination exceed 0.9 for all seasons during the solar maximum phase.

These results show that NeQuick-2 performance depends strongly on both season and solar activity level. They confirm the model's robustness in representing the ionospheric E-layer under high solar activity while highlighting persistent limitations in reproducing equinoctial conditions and sunset conditions over the African equatorial region.