Assessing Space Weather Phenomena using GPS ionospheric TEC analysis

Space weather events significantly disrupt Earth's ionosphere, affecting atmospheric properties and degrading radio signal quality. This study investigates ionospheric Total Electron Content (TEC) variations to characterize space weather phenomena, focusing on the F2 layer. Using GNSS dual-frequency observations and ground- and satellite-based solar indices, the research examines events such as the geomagnetic storms of March 24, 2023, and April 24, 2023, and the solar flare of March 3, 2023.

TEC time-series analysis reveals latitudinal and semi-annual variations in ionization, with maximum TEC during equinoxes due to enhanced thermospheric circulation and dominance of atomic oxygen. In contrast, solstice months exhibit reduced ionization efficiency due to asymmetric heating and dynamics. Correlation analysis during the March storm identifies a significant impact of geomagnetic disturbances, with a negative correlation (-0.44) between the Dst index and TEC. The April storm shows a stronger positive correlation (0.41) between the Kp index and TEC, highlighting the heightened ionospheric response to global geomagnetic activity.

Wavelet analysis uncovers latitudinal periodicities linked to solar rotation cycles. Equatorial regions exhibit TEC modulation with a 22.7-day periodicity due to intense solar EUV radiation, while mid-latitudes show a 24.7-day periodicity influenced by geomagnetic storms and solar radiation. High-latitude regions are dominated by geomagnetic activity, with TEC fluctuations modulated at a 27.9-day periodicity by high-speed solar wind interactions and auroral activity. These findings underscore the complex interplay between solar activity, geomagnetic disturbances, and ionospheric dynamics, providing insights critical for improving space weather prediction models.