Multi-Latitudinal PRN-Based GNSS-TEC Analysis of Ionospheric Perturbations during the 21 August 2017 Solar Eclipse

The 21 August 2017 Great American solar eclipse provided a unique opportunity to examine ionospheric disturbances under rapid and controlled solar radiation reduction. In this study, GNSS-derived Total Electron Content (TEC) observations from three representative stations located at low latitude (BOGT), mid latitude (P398), and high latitude (NYAL) were analyzed to investigate the spatial and temporal characteristics of eclipse-induced plasma variability. Distinct TEC depletion was recorded at all stations during the eclipse interval, with the largest response over the low-latitude sector and comparatively weaker but more irregular changes at high latitudes. To identify short-term disturbances, detrended TEC residuals and continuous wavelet transform analyses were performed. The results revealed enhanced oscillatory activity near and after the maximum eclipse phase, with dominant periodicities in the range of 40–65 min. These signatures indicate the presence of medium-scale traveling ionospheric disturbances (TIDs), most likely generated by eclipse-driven atmospheric gravity waves (AGWs) and subsequent ionosphere-thermosphere coupling. The comparative multi-latitudinal analysis demonstrates that the eclipse response was strongly modulated by regional background ionization and latitude-dependent electrodynamic processes. This study highlights the capability of GNSS observations to capture both large-scale electron density depletion and mesoscale wave perturbations, providing valuable insight into transient ionospheric dynamics during sudden solar forcing events.