Global VTEC Maps of the Geomagnetic Storm in May 2024 and Their Application to Study the Evolution of the Ionospheric and Plasmaspheric VTEC Distribution

We present an expansion of the near real-time VTEC maps over Europe produced by the ROB-IONO software (Bergeot et al., 2014) from multi-constellation GNSS data to a global scale. For this purpose, we use median polish kriging to interpolate the VTEC data, which is a purely statistical technique that does not rely on background ionospheric models. We compare the derived global map products to those of other services and the entire global VTEC dataset for validation.

The generated maps are used to study the geomagnetic storm which commenced on 10 May 2024, with a focus on identifying storm-time signatures in the VTEC maps by comparing to the median maps from the preceding solar rotation period. Additionally, we investigate the changes in distribution between the ionospheric and plasmaspheric VTEC at varying latitudes before and during the storm by comparing with COSMIC-2 and EISCAT data to isolate the plasmaspheric contribution.