Abstract
Abstract. Our capability to model the near-space physical phenomena has gradually reached a level enabling module-based first-principles modeling of geomagnetically induced electromagnetic fields and currents from upstream solar wind to the surface of the Earth. As geomagnetically induced currents (GIC) pose a real threat to the normal operation of long conductor systems on the ground, such as high-voltage power transmission systems, it is quite obvious that success in accurate predictive modeling of the phenomenon would open entirely new windows for operational space weather products. Here we introduce a process for obtaining geomagnetically induced electromagnetic fields and currents from the output of global magnetospheric MHD codes. We also present metrics that take into account both the complex nature of the signal and possible forecasting applications of the modeling process. The modeling process and the metrics are presented with the help of an actual example space weather event of 24–29 October 2003. Analysis of the event demonstrates that, despite some significant shortcomings, some central features of the overall ionospheric current fluctuations associated with GIC can be captured by the modeling process. More specifically, the basic spatiotemporal morphology of the modeled and "measured" GIC is quite similar. Furthermore, the presented user-relevant utility metrics demonstrate that MHD-based modeling can outperform simple GIC persistence models.
Highlights
Over the past few years there has been great progress in establishing extensive space weather frameworks having an ambitious goal of module-based modeling of the space weather phenomenon from the Solar surface to the planetary ionospheres
Much of space weather is covered within the Solar surface and Earth’s ionosphere, the space weather phenomena do not end there; the processes extend down to the surface and below the surface of the Earth in terms of geomagnetic induction driven by variations in the near-space current systems
Based on the sole impact of the famous March 1989 storm on the North American power transmission system (e.g., Czech et al, 1992; Bolduc, 2002), it is safe to say that geomagnetically induced currents (GIC) is one of the most important space weather hazards and that need for science-based mitigation capabilities is real
Summary
Over the past few years there has been great progress in establishing extensive space weather frameworks having an ambitious goal of module-based modeling of the space weather phenomenon from the Solar surface to the planetary ionospheres (see Toth et al, 2005, and references therein). The following process was used to compute the induced electromagnetic fields at the surface of the Earth (see Fig. 2): 1.) Ionospheric currents produced by the BATS-R-US were transformed from geomagnetic coordinates to geographic coordinates (GEO). 1-D approximation has been shown to be valid in numerous space weather-related geomagnetic induction studies (see e.g., Viljanen et al, 2004; Pulkkinen and Engels, 2005), there are important special cases where horizontal gradients cannot be neglected Such cases include, for example, boundaries of continents and deep oceans where the so-called “coast effect” plays an important role in modifying the induced electromagnetic fields (e.g., Beamish et al, 2002; Olsen and Kuvshinov, 2004). With the introduced modeling process the numerical bottleneck is the magnetospheric MHD, not the computations associated with the geomagnetic induction
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