The ionosphere is a highly dynamic plasma region of Earth's upper atmosphere that profoundly impacts the propagation of trans-ionospheric radio waves. Because it can refract, diffract, or scatter radio waves, understanding its state and structure is critical to the reliability of modern satellite-based communication and navigation systems.

Global Navigation Satellite System (GNSS) Radio Occultation (RO) is a limb-sounding technique that exploits signals transmitted by GNSS constellations and received by Low Earth Orbit (LEO) satellites. While traditionally used to retrieve neutral atmosphere thermodynamics, GNSS-RO signal is highly sensitive to ionospheric electron density gradients and the rapid signal amplitude and phase fluctuations, known as scintillation, caused by plasma irregularities.

This licentiate thesis focuses on the equatorial ionosphere, specifically targeting the detection and three-dimensional localization of Equatorial Plasma Bubbles (EPBs). Utilizing GNSS-RO measurements from the GRAS receivers onboard the Metop satellite constellation, a segmented wave-optics back-propagation algorithm is developed to localise the ionospheric irregularities responsible for signal scintillation along the ray path. The retrieved locations are subsequently converted into geodetic coordinates and independently validated against far-ultraviolet airglow observations. Finally, this methodology is scaled to automate detection and produce a comprehensive study of EPB occurrence, advancing the understanding of low-latitude ionospheric electrodynamics and the spatial distribution of space weather hazards.