Drivers of Geomagnetically Induced Current Bursts: The Kola Peninsula Experience

Abstract:

Large-scale space weather disturbances are potentially risky for space and ground technologies. Generation of geomagnetically induced currents (GICs) related to abrupt changes of the geomagnetic field is one of the most significant space weather factors for power transmission lines. However, the highest risk of GIC may be related not to global processes with enormous energy yield, but to more localized and rapid processes. Such localized and fast disturbances embedded into the global magnetospheric processes may be the actual drivers of GIC bursts. The system deployed by Polar Geophysical Institute (Apatity) for recording of GIC in a deadline transformer of the power line elongated in latitudinal direction at Kola peninsula provided many examples of GIC bursts. The GIC response to magnetospheric drivers has a maximum at a time scale about 2-10 min, that is in the ULF frequency range. The impulsive geomagnetic disturbances may be associated with substorm onsets and subsequent activations, magnetic perturbation events – isolated ~10 min disturbances, geomagnetic Ps6/Pi3 pulsations – quasi-periodic series of impulses with duration ~10-20 min, and narrow band Pc5 pulsations (2-7 mHz). Though the power of such processes is lower than the power of magnetospheric storms and substorms, the rapidly varying electromagnetic fields of these events can induce a significant GIC. These large localized disturbances on short timescales may be imagined like space tornadoes in analogy to terrestrial weather. The intense Pi3/Ps6 pulsations and global Pc5 waves may be responsible for the extreme once-per-century electrotellutic fields.