Comparison of IRI-2020 and NeQuick2 TEC Estimates at the BF01 Station in Ouagadougou on Selected Recurrent Geomagnetic-activity Days of Solar Cycle 24

Abstract

Total electron content (TEC) varies with solar activity, season, local time, and geomagnetic conditions. This study compares hourly TEC estimates from IRI-2020 and NeQuick2 at BF01, Ouagadougou (12°37′N, 1°51′W), for selected days of recurrent geomagnetic activity during solar cycle 24. Recurrent days were identified using the Aa > 40 nT criterion applied in the original Legrand-Simon classification; because Zerbo et al. (2012) later lowered the minimum Aa threshold for recurrent activity to 20 nT, the analysed dates represent a conservative higher-activity subset. The comparison is organised by solar-cycle phase and season. IRI-2020 is used only as the denominator for inter-model relative differences and not as observational ground truth. No qualifying dates occurred during the ascending phase. At solar minimum and maximum, the two models produce different diurnal profile morphologies, whereas both produce noon-bite-out profiles during the descending phase. NeQuick2 is generally lower than IRI-2020 during daytime and higher at several nighttime or pre-dawn hours. The largest percentage differences occur near dawn, when absolute TEC is small and ratio-based differences are especially sensitive. Seasonally, profile agreement is greatest in winter. Both models show nighttime equinoctial asymmetry and winter-anomaly signatures, while the semi-annual pattern is nearly continuous in IRI-2020 but weakens around local noon in NeQuick2. Because independent BF01 GNSS-derived TEC observations were not incorporated into the present analysis for the selected dates, the results constitute a descriptive inter-model comparison and do not establish the observational accuracy of either model.