Comparing IRI-2020 modeled hmF2 and ionosonde measured hmF2 variabilities during the geomagnetically disturbed period of solar cycle 24 over Grahamstown, in South Africa

Abstract The ionosphere's electron density, particularly the height of the F2 layer's peak electron density (hmF2), is critical for radio wave propagation and satellite communication. Accurate prediction of hmF2 is crucial, especially during geomagnetic disturbances, which can significantly affect ionospheric behavior. This study compared hmF2 values predicted by the ionospheric IRI model with real measurements from ionosondes during geomagnetic storms. We assessed discrepancies between modeled and observed hmF2 values across three distinct geomagnetic storm events, 22–25 October 2009, 26–29 August 2014, and 18–22 February 2014. We categorized geomagnetic disturbances using the Ap and Dst indices. Results indicated that while both SHU-2015 and AMTB-2013 models show varying degrees of accuracy, the SHU-2015 model generally outperforms AMTB-2013 in predicting hmF2, with lower root mean square errors and percentage deviations. The study highlights the need for ongoing model refinement and improved real-time data integration to enhance predictive accuracy during geomagnetic disturbances.