Investigation of Geomagnetically Induced Current activity indices using Information Theory

Geomagnetically Induced Currents (GICs) are a manifestation of space weather events at ground level. GICs have the potential to cause power failures in electric grids. The GIC index is a proxy of the ground geoelectric field derived solely from geomagnetic field data. Information Theory (IT) can be used to shed light on the dynamics of complex systems, such as the coupled solar wind-magnetosphere-ionosphere-ground system. Previously, we have performed block entropy analysis of the GIC activity indices at middle-latitude European observatories around the St. Patrick's Day March 2015 intense magnetic storm and Mother's Day (or Gannon) May 2024 super-intense storm. We found that the GIC index values were generally higher for the May 2024 storm, indicating elevated risk levels. Furthermore, the entropy values of the SYM-H and GIC indices were higher in the time interval before the  storms than during the storms, indicating transition from a system with lower organization to one with higher organization. Recently, IT has proven itself as a powerful approach to study causal relationships among various coupled complex systems. Here, we use Conditional Mutual Information as a measure of causality which is, indeed, the mutual information between the cause and the future of the effect variable, conditioned on the history of the effect variable, to investigate the possible coupling direction and pattern of interactions among different GIC indices, and various solar wind variables and geomagnetic activity indices.