Advancing GNSS tomography for three-dimensional ionospheric monitoring

Global Navigation Satellite System (GNSS) tomography has emerged as a powerful technique for reconstructing three-dimensional ionospheric electron density distributions using multi-satellite and multi-receiver slant total electron content (STEC) measurements. Unlike traditional two-dimensional approaches, this method enables the resolution of complex ionospheric structures such as equatorial plasma bubbles, storm-enhanced densities, and traveling ionospheric disturbances with improved spatial and temporal resolution, offering critical insights for space weather monitoring and mitigation of GNSS positioning errors.Three near-term ionospheric challenges ionospheric problems addressable in the near term include: (1) enhancing vertical resolution via multi-source data fusion, integrating measurements from emerging and planned LEO mega-constellations (e.g., Starlink) with ground-based GNSS and ionosonde measurements to overcome the inherent vertical ambiguity of pure ground-based tomography; (2) real-time disturbance monitoring using machine learning, deploying LSTM models or physics-informed neural networks to predict sub-hourly electron density variations from tomography datasets, enabling proactive mitigation of GNSS positioning errors during ionospheric storms; and (3) validating topside ionosphere models, leveraging recent CHAMP, GRACE-FO and COSMIC-2 radio occultation data products to constrain and evaluate empirical models such as IRI in the under-sampled topside region, improving space weather specification fidelity.This Research Topic welcomes contributions advancing GNSS tomography methodologies and their applications in ionospheric science. Specific themes include: (i) novel tomographic algorithms addressing sparse-data reconstruction, particularly machine learning-assisted inversion and multi-scale regularization techniques; (ii) multi-source data fusion incorporating LEO mega-constellations, radio occultations, and ground-based sensors; (iii) real-time ionospheric monitoring and forecasting for operational space weather operational services; (iv) validation studies against independent measurements (ionosondes, ISR, and rockets) and assimilation into physics-based models; and (v) climatological analyses of ionospheric irregularities, storm dynamics, and long-term trends. We invite Original Research, Reviews, and Brief Research Reports that demonstrate rigorous validation, interdisciplinary approaches, or transformative potential for operational space weather applications. Topic editors: Yafei Ning, Kaili Song, Yong Wang Source: https://www.frontiersin.org/research-topics/85646/advancing-gnss-tomography-for-three-dimensional-ionospheric-monitoring