Development of Global VTEC Maps at the Royal Observatory of Belgium: Applications for Space Weather and Long-Term Ionospheric Trends

We present our work at the Royal Observatory of Belgium to develop a novel, data-driven approach to generate global near real-time VTEC maps using multi-constellation GNSS data, extending the capabilities of the established ROB-IONO software (Bergeot et al., 2014). Our method employs a multi-step downsampling and data reduction algorithm, combined with median polish kriging, to produce global VTEC maps. This purely data-driven approach, which does not rely on ionospheric models or prior time steps as input, enables near real-time mapping and robust analysis of large-scale ionospheric and plasmaspheric trends.
These maps are particularly valuable for studying the ionosphere-plasmasphere system during geomagnetic storms and other disturbed conditions, such as the May 2024 geomagnetic storm. By integrating complementary datasets (e.g., COSMIC-2, ionosondes), we can disentangle ionospheric and plasmaspheric contributions to VTEC, offering new insights into their dynamic behavior and changes in distribution during space weather events. The downsampling and median polishing techniques also enable future analysis of long-term GNSS datasets, facilitating studies of decadal-scale trends in the ionosphere-plasmasphere system, which are critical for understanding changes in the climatology of the upper atmosphere and the impacts of solar cycle variations. This global VTEC mapping capability not only enhances space weather monitoring but also provides a powerful tool for investigating long-term ionospheric variability, with uses for both scientific research and operational applications.