Modelling the ground effects of a Carrington-class geomagnetic storm using global geospace simulation

An extreme geomagnetic storm of a magnitude comparable to the historical Carrington event of 1859 would pose a substantial threat to ground-based technological infrastructure, particularly to electrical power transmission systems. A previously published simulation by Blake et al. (2021, Space Weather, doi:10.1029/2020SW002585) reconstructed the magnetic field observations at Colaba, India, during the Carrington storm and provided estimates of magnetic field variations around the world. Building upon this work, we employ a physics-based, first-principles modelling approach to estimate the induced geoelectric field in the Fennoscandian region. This approach uses a detailed three-dimensional model of the Earth’s subsurface electrical conductivity.

To contextualize the severity of a potential Carrington-class event, we compare the resulting geoelectric field estimates with those modelled due to the geomagnetic storm of October 2003 (commonly referred to as the Halloween storm) - one of the most intense geomagnetic disturbances recorded in the past 100 years. The Halloween event is particularly well-suited for comparison due to the availability of high-resolution, spatially dense magnetometer data across Northern Europe. Our analysis indicates that the maximum geoelectric field magnitudes modelled for a Carrington-class storm in Fennoscandia could exceed those produced during the Halloween storm by a factor of approximately 4-10. These findings underscore the elevated geoelectric hazard posed by such extreme geomagnetic activity, especially in regions with high-latitude infrastructure.