GIC research at the Finnish Meteorological Institute: Untangling the interaction between the geospace and the conducting ground

by Liisa Juusola (Finnish Meteorological Institute, Helsínquia)

Tuesday 9 Jun 2026, 15:30 → 16:30 Portugal

Sala de Conferências (Departamento de Física FCTUC)

Geomagnetically induced currents in grounded technological conductor networks, such as power grids, are a common hazard at high latitudes. Estimation of the geoelectric field that drives GIC requires 1) information on the driving external magnetic field variations, 2) information on the three-dimensional conducting ground, and 3) a computationally feasible method for calculating the geoelectric field. At the Finnish Meteorological Institute, we model the geoelectric field in Fennoscandia using observations from a spatially dense magnetometer network, a detailed 3-D ground conductivity model, and a physics-based induction simulation code. The modelled geoelectric field is provided to the local power grid operator, who can estimate GIC in their system without needing to share any classified technical descriptions. While the available long time series of geomagnetic observations provide valuable information on the drivers of geoelectric field peaks, they cannot yield information on extreme geomagnetic storms that have not yet occurred during the modern observational era. We have estimated the geoelectric field response to such an event using the external geomagnetic variations from a physics-based geospace simulation of the 1859 Carrington storm to drive our induction simulation. Our results indicate that peak geoelectric fields during a Carrington-level storm in Fennoscandia could be roughly four to ten times stronger than those generated during the Halloween storm of 2003, which was one of the strongest space weather events of the last 100 years. Our future plans include similar modelling of the "perfect sudden commencement" as well as studying the two-way feedback between the ground and the ionosphere.