Dottorato in ASTRONOMIA

Titolo della tesi: Ionospheric Plasma Dynamics: Investigating Solar, Geomagnetic, and Seasonal Influences with Emphasis on GPS Signal Interruptions

The high-latitude ionosphere is a region of intricate plasma dynamics, deeply influenced by the local topology of the geomagnetic field forming a direct connection with the magnetosphere and the solar wind. This region manifests distinct characteristics under varying solar and geomagnetic conditions, directly influencing radio communication and satellite navigation systems. This study delves into the plasma dynamics across various scales, from a global perspective down to meso- and small-scale structures, emphasizing their potential impact on technologies like Global Navigation Satellite Systems (GNSS). The foundation of this comprehensive study was laid through continuous monitoring of plasma conditions over the past decade, made possible by the ESA Swarm mission. Firstly, the research employs the Multivariate Empirical Mode Decomposition method to deconstruct the high-latitude electron density distributions. This analysis reveals fundamental modes associated with ionospheric large-scale dynamics, displaying distinct dependencies on seasons and geomagnetic activity. Then, the study explores the influence of plasma irregularities on ionospheric dynamics, specifically focusing on their role in originating pressure-gradient currents, which can have an effect on geomagnetic field measurements. Finally, the research addresses disruptions in GNSS signals, identifying the underlying irregularities and their characteristics. Notably, the study establishes a connection between GPS Loss-of-Lock events and a specific class of turbulent irregularities. Furthermore, it provides deeper insights into their climatological dependencies. These findings extend their relevance by shedding light on potential mitigation strategies for this damaging space weather effect. This comprehensive investigation significantly advances our comprehension of ionospheric dynamics in this complex region profoundly influenced by space weather phenomena. It offers valuable insights for mitigating various adverse effects, pushing the boundaries of our understanding of the high-latitude ionosphere. Moreover, many aspects of this study can potentially be extended to explore the ionospheres of other planets.