Falayi EO and Beloff N
Keywords: Time derivatives of geomagnetic fields, GIC (Geomagnetic induced current), higher latitudes
Abstract: This report investigates variations in time derivatives of the geomagnetic field observed during great storms known to have caused disruption and to have had other adverse effects on power grids. The geomagnetic storms considered were those of 24th November 2004, 30th October 2003 and 28th October 2004, which occurred during the Autumnal event, and also 7th April 2000 and 31st March 2001 which occurred during the Spring events. Geomagnetic field variations are associated with geoelectric field variation at the surface of the Earth which is influenced by the conductivities of different structures of the Earth’s interior. The induced electric field is proportional to the rate of change of the geomagnetic field, which explains why many researchers have used time derivatives of the geomagnetic field as a measure of GIC strength. Koen and Gaunt (2002) established that variation exceeding 30nT/min of the time derivatives of the geomagnetic field component appears to be significant, causing undesirable consequences in power grids.
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