Surface electric fields for North America during historical geomagnetic storms

Abstract

[1] To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms-the 1989 "Quebec" storm and the 2003 "Halloween" storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.

Influence of spatial variations of the geoelectric field on geomagnetically induced currents

“…For comparison, Langlois et al (1996) reports the maximum measured value of 1.7 V/km in Québec, Canada, within a 500-day period, in an area that corresponds to South Finland in geomagnetic latitudes. Model calculations in North America by Wei et al (2013) and Nikitina et al (2016) indicate values up to 2-5 V/km. We remind that the electric field is very sensitive to the conductivity, so different ground models can produce fields with clearly different magnitudes when the same magnetic field is used as input.…”

“…The geoelectric field varies rapidly temporarily and spatially as demonstrated, for example, by Beggan et al (2013), Bedrosian and Love (2015), Wei et al (2013) and Wang et al (2016) for regional and continental scales, and by Püthe and Kuvshinov (2013) and Ngwira et al (2015) for global scales. Temporal variations are due to time variations of space currents and are connected with time variations of the geomagnetic field by Faraday's law.…”

How severe space weather can disrupt global supply chains

“…They usually increase with geomagnetic latitude, transmission line length and voltage, but decrease with distance to the ocean and increased ground resistivity (Wei et al, 2013). Space-weather events also cause auroras, usually in two small ovals around 65 (±5) degrees northern and southern latitude that vary in size, location and intensity during geomagnetic storms.…”

“…These frequencies are comparable to other severe natural disasters, such as large earthquakes and volcanic eruptions. Power grids typically experience problems when the rate of change of the magnetic field exceeds a 100-200 nT min −1 (Wei et al, 2013). Occurring today, the Quebec 1989 event or the 1859 Carrington event would have a profound impact on the daily lives of millions of people, both through direct effects and via the impacts to the globalized economic production system.…”

“…The estimated damage to the power system in Quebec in 1989 is in the range of USD 2 billion, whilst the total damage is estimated to be around USD 13 billion (Kappenmann, 2010;Boteler, 1998). Another study estimates that the economic losses in North America and Europe for a power blackout for 5 months caused by a Carrington-like event would be between USD 0.5 and 2.6 trillion (Lloyd's, 2013;Wei et al, 2013). It has also been estimated that a North American power grid blackout would result in a GDP loss in the USA of about USD 30 billion per day, accumulating to over USD 10 trillion per year (Lloyd's, 2013).…”