gic/usgs

The gic/usgs data collection provides access to streaming geomagnetic field data updated once per minute. Data streams from a network of measurement sites each streaming on four channels, reporting the magnitude of the earth’s geomagnetic field (in nanoteslas) in the North, South, and vertical directions.

The data are provided to support studies of geomagnetically induced current (GIC) on the grid, caused by geomagnetic disturbances (GMDs) in the Earth’s magnetic field.

What are GMDs?

Geomagnetic disturbances are instances of variability in the Earth’s geomagnetic field. GMDs occur naturally due to electrically charged particles emitted by the sun suring solar flares (or solar weather) events. These particles are typically deflected by the Earth’s geomagnetic field to the poles – this is what causes the aurora borealis or Northern Lights pictured below.

GICs

Following Faraday’s law of induction, changes in the magnetic field at the Earth’s surface can cause an induced current in the electrical grid. These “geomagnetically induced currents” are DC currents that, during a severe or prolonged GMD, may be damaging to grid components.