Geomagnetically induced currents in central Europe

Eruptive events on the Sun interacts with the magnetosphere and can affect even the Earth-bound structures such as power transmission networks via geomagnetically induced electric currents (GICs). We quantify the geomagnetic activity by the K-index computed from local measurements of the geomagnetic field and investigate its effects on the Czech electric power grid represented as disturbances recorded in the maintenance logs of the power network operators in course of last 12 years. In data sets recording the disturbances on high and very high voltage power lines, we found a statistically significant increase of anomaly rates within tens of days around maxima of a geomagnetic activity compared to the adjacent activity minima. Moreover, we modeled GICs for two (east-west and north-south oriented) high-voltage transmission lines in the Czech Republic and found surprisingly high values of currents, in the order of tens of amperes. Based on in-situ observations, we study propagation and properties of the largest CMEs and their relation to the disturbances in the transmission networks of the Central European countries. Our results provide an evidence that GICs may affect the occurrence rate of anomalies registered on power-grid equipment even in the mid-latitude countries.