Estimating GIC from a single observatory at high and mid latitudes

Space weather effects on grounded infrastructure such as high-voltage power networks have been well documented over the past three decades. Current research on Geomagnetically Induced Currents (GIC) seeks to understand both the detailed effects of extreme geomagnetic storms on transformers as well as methods for nowcasting or forecasting the magnitude of such events in real-time, particularly where only sparse measurements may be available. We examine the use of remote observatories (up to 1000 km away) to model the GIC flowing in two hypothetical power grids. The first grid is the benchmark test grid of Horton et al (2012) with 15 ‘transformers’ and the second is a simplified version of the UK power network with around 250 nodes. We place the grids at high geomagnetic latitudes in the auroral to sub-auroral zone around Hudson Bay in Canada and use data from three local magnetic observatories (Baker Lake: BLC; Fort Churchill: FCC and Poste de-la-Baleine: PBQ). We use magnetic data from three large storms of March 1989, June 1991 and October 2003 and a simple land/sea conductance model to calculate the geo-electric field using the thin-sheet modelling method. The GIC flowing with each grid is computed, both separately and jointly, from the magnetic field recorded at the observatories. We find that although the correlation between the GIC flows computed from the different observatories varies with distance to the instrument, the magnitude of the GIC are similar to within around 20%. This suggests that remote observatories can provide useful information for nowcasting GIC flow in a power grid