Geomagnetic and Telluric Field Variability as a Driver of Geomagnetically Induced Currents
We analyse temporal and spatial variability of geomagnetic and telluric electric fields in the Eastern Fennoscandia. These variations are compared with available geomagnetically induced current (GICs) measurements in electric power transmission lines at Kola Peninsula and Karelia. The information on impedance tensors is provided by the electromagnetic sounding array BEAR. We synthesize the telluric E-field from geomagnetic field variations, using the complex impedance tensor. We analyze geomagnetic and E-field variations at several sites for different space weather events: magnetic storm and Pi3 pulsations. We compare the spectral content of geomagnetic, telluric, and GIC variations. This comparison shows that the commonly used as a measure of GIC disturbances time derivative of geomagnetic field dB/dt does not totally control them. The suppression of high-frequency component in the GIC spectrum as compared with dB/dt variations is determined by the frequency-dependent character of the crustal geoelectric response.
KeywordsGIC Magnetic storm Telluric fields
This study is supported by the grant 16-17-00121 from the Russian Science Foundation. We acknowledge the data from the deep sounding project BEAR and IMAGE array (http://space.fmi.fi/image). The maintenance of the GIC recording system by the Polar Geophysical Institute and Center of Physical and Technical Problems of the Northern Energetics is supported by the grant 17-48-510199 from the Russian Fund for Basic Research and Murmansk Region Government.
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