Geomagnetically Induced Currents
GIC - A Space Weather Effect
Lund Space Weather Center

More about GICMore about GICSolar Wind, Geomag. field and GICEarth

These pages gives a very brief description of GIC as a space weather phenomena. To learn much more about Space Weather, click here.

Geomagnetically Induced Currents (GIC) - Semi-direct currents that can destroy high-voltage transformers, and even cause a complete power system black-out. The currents are a consequence of mass ejections in the solar corona, so called Coronal Mass Ejections (CME). If and when the CME passes the Earth, the CME will to some degree penetrate into the Earth's magnetosphere and cause geomagnetic substorms. During the substorms, currents of a million Amperes or more arise in the Earth's ionosphere on high latitudes, like over Canada, Scandinavia, Scotland and northern Russia. These ionospheric currents, called electrojets, induces a varying magnetic field and thereby an electric field in the surface of the Earth. Since high voltage power systems are grounded through the transform neutrals, the electric fields drives semi-direct currents through the transformers and the power lines connecting them. Read more about GIC, their cause and effects on the following pages. You can also see a real-time GIC forecast, that shows how high GIC we can expect in a power line in the south of Sweden right now. If it exceeds about 50 Ampere, there might be some disturbances in the power system.

...causes this...
...and this.
A Coronal Mass Ejection from the Sun.
A GSU (generation step-up) transformer at a nuclear plant in New Jersey in which a 1,200 MVA, 500kV bank was damaged beyond repair.
Aurora over Stockholm, Sweden, on the 6th of April, 2000.
Picture taken by the LASCO instrument onboard SOHO.
Text and picture borrowed from John Kappenman and Minnesota Power Electric.
Picture from Svenska Dagbladet.