Long-Term Statistical Analysis of Ionospheric Variability Over Egypt Using High-Precision GNSS Data

This study investigates the ionospheric dynamics over Egypt—a region uniquely positioned between low and mid latitudes beneath the northern crest of the Equatorial Ionization Anomaly (EIA). Utilizing three years (January 2022 to February 2025) of high-accuracy Vertical Total Electron Content (VTEC) data from 30 high-end Global Navigation Satellite System (GNSS) stations—the first comprehensive, continuous, and reliable dataset covering the entire country—we conducted a detailed statistical analysis to identify diurnal and seasonal trends. We compared the observed GNSS-derived VTEC with predictions from the IRI2020 model under various solar activity conditions, revealing significant disparities during both quiet and disturbed periods across multiple timescales. In addition, solar and geomagnetic data were integrated to accurately correlate ionospheric behavior with geomagnetic activity. Our findings not only unveil distinct regional patterns and model shortcomings but also provide crucial insights into the ionosphere’s response to different influences. This study marks a pioneering effort in Egypt to advance space weather forecasting and ionospheric modeling.