Evaluation of Automated Spread–F (SF) Detection over the Midlatitude Ionosphere

The present study evaluates an automated Spread–F (SFP) detection algorithm by integrating SF-related (QF, FF) and ionospheric parameters (hmF2, h’F), acting as an indicator for SF events, from SAO Explorer auto-scaled (ARTIST) data, compared to manually identified SF events (SFM) across nine European midlatitude ionospheric stations. The stations were categorized into four latitude sectors to evaluate latitudinal influence in an analysis within the period 2009–2021 from low to high solar activity levels. The results revealed an inverse correlation between solar activity and agreement between SFP and SFM, with stronger agreement during the solar minimum. In the 55°–60° N sector, the SFP–SFM match varied from 71% during the solar minimum to 47% during the solar maximum, with overestimation associated with LSTID activity. In the 50°–55° N sector, agreement ranged from 66% to 56%, with overestimation associated with MSTIDs and oblique traces. The 40°–45° N sector exhibited the highest variability (89% to 42%), where Satellite Traces (STs), Multiple Reflected Echoes (MREs), and spread Es led to both over– and underestimations. In the 35°–40° N sector, agreement dropped to 30% during the solar maximum, with wintertime overestimation and summer underestimation significantly characterized by STs, MREs, and Es–layer interference.