On the possibility of high‐level transient coronal mass ejection–induced ionospheric current coupling to electric power grids

[1] Short‐time (<10 s) ionospheric current fluctuations are hypothesized to occur due to a coronal mass ejection that can induce high‐level transient voltages on long overhead power transmission lines. This hypothesis is first supported by reviewing published literature and recent magnetometer measurements, both of which indicate the existence of such rapid ionospheric current fluctuations. Then results are reported of a new full‐vector three‐dimensional Maxwell’s equations finite‐difference time‐domain (FDTD) model of the global Earth‐ionosphere system during a solar storm. This model naturally treats transient electromagnetic fields and waves unlike previous quasi‐DC steady state or sinusoidal steady state analyses. Furthermore, this model accounts for the geometrical and electrical properties of the entire global Earth‐ionosphere system, including details of the global topography and bathymetry, rather than focusing upon a particular continental region as for previous analyses. The FDTD modeling results provide new and useful information, such as that the lithosphere conductivity has almost no impact on the induced transient (short timescale) surface geoelectric fields resulting from capacitive or electric field coupling mechanisms. This is counter to the previously analyzed magnetic field coupling mechanisms involving the (long timescale) induction of geomagnetically induced currents, which heavily depend on the lithosphere conductivity structure. The modeling results presented herein are sufficiently significant to warrant measurements of rapid ionospheric current fluctuations at timescales much shorter than considered at present, even less than 1 s.