A new window on the ionosphere: A LOFAR perspective, from geomagnetic storms to statistical trends

The Low Frequency Array (LOFAR) radio telescope, while primarily conceived for astronomical observation, offers a uniquely powerful modality for high-resolution ionospheric research. The fundamental principle relies on analysing amplitude scintillations of trans-ionospheric radio signals originating from cosmic sources. As these wavefronts traverse the ionosphere, they are perturbed by localised plasma density variations, creating complex diffraction patterns that LOFAR is uniquely configured to characterise. A primary objective of this work was to rigorously validate LOFAR as a robust instrument for ionospheric monitoring. Comprehensive cross-validation was performed using established geo-space instrumentation, including Global Navigation Satellite Systems (GNSS), ionosondes, and magnetometers. By directly comparing LOFAR-derived metrics against these standard systems, the study demonstrated strong correlations that confirm not only the feasibility but also the precision of LOFAR for routine diagnostics. Building on this validation, the research extended LOFAR’s utility to the domain of extreme space weather. A novel algorithm was developed to determine the effective altitude of irregularity layers—a critical parameter for accurately modelling scintillation phenomena. This method was proven robust by processing data from the Mother’s Day Superstorm, the most intense geomagnetic storm of the past two decades, showcasing a capability to probe dynamics under disturbed conditions often opaque to other techniques. Finally, a comprehensive statistical analysis was performed on a dataset spanning over two years of continuous observations. Covering a wide spectrum of geomagnetic conditions, this investigation yielded significant insights into the morphological characteristics of ionospheric irregularities, specifically establishing their dominant magnetic field alignment and anisotropic scale sizes. Collectively, these contributions establish LOFAR as an indispensable tool for space weather research, advancing the understanding of ionosphere-magnetosphere coupling and its impacts on technological systems.