Statistical Properties of the Geomagnetic Field Variations and Geomagnetically Induced Currents

The relationships between variations of geomagnetic field and geomagnetically induced current (GIC) are studied using data from the station for registration of GIC in the electric transmission line and the IMAGE magnetic observatory. A highest correlation of GIC intensity (R > 0.7) is found with the field variability vertical bar dB/dt vertical bar, whereas the correlations of GIC with the time derivatives of X and Y components are about the same. The diurnal variations of hourly values of geomagnetic field variability and GIC intensity have a wide night maximum associated with the substorm activity, and a wide morning maximum presumably caused by geomagnetic pulsations of the Pc5-Pi3 type. A regression linear model is constructed to estimate GIC magnitude from the local time derivative of geomagnetic field. The statistical distributions of the probability density of vertical bar dB/dt vertical bar and GIC correspond to the log-normal law. On the basis of the constructed distributions the probabilities of extreme values of GIC and vertical bar dB/dt vertical bar are estimated.