Abstract
We present a methodology that allows researchers to simulate in real time the spatiotemporal dynamics of the ground electric field (GEF) in a given 3‐D conductivity model of the Earth based on continuously augmented data on the spatiotemporal evolution of the inducing source. The formalism relies on the factorization of the source by spatial modes (SM) and time series of respective expansion coefficients and exploits precomputed GEF kernels generated by corresponding SM. To validate the formalism, we invoke a high‐resolution 3‐D conductivity model of Fennoscandia and consider a realistic source built using the Spherical Elementary Current Systems (SECS) method as applied to magnetic field data from the International Monitor for Auroral Geomagnetic Effect network of observations. The factorization of the SECS‐recovered source is then performed using the principal component analysis. Eventually, we show that the GEF computation at a given time instant on a 512 × 512 grid requires less than 0.025 s provided that GEF kernels due to pre‐selected SM are computed in advance. Taking the 7–8 September 2017 geomagnetic storm as a space weather event, we show that real‐time high‐resolution 3‐D modeling of the GEF is feasible. This opens a practical opportunity for GEF (and eventually geomagnetically induced currents) nowcasting and forecasting.
Plain Language Summary
The solar activity in the form of coronal mass ejections leads to abnormal fluctuations of the geomagnetic field. These fluctuations, in their turn, generate so‐called geomagnetically induced currents (GIC) in electric power grids, which may pose a significant risk to the reliability and durability of such infrastructure. Forecasting GIC is one of the grand challenges of the modern space weather studies. The critical component of such forecasting is real‐time simulation of the ground electric field (GEF), which depends on the electrical conductivity distribution inside the Earth and the spatiotemporal structure of geomagnetic field fluctuations. In this paper, we present and validate a methodology that allows researchers to simulate the GEF in fractions of a second (thus, in real time) irrespective of the complexity of the Earth's conductivity and geomagnetic field fluctuations models.
Key Points
We present the formalism of real‐time modeling of the ground electric field (GEF) excited by temporally and spatially varying source
The formalism relies on the factorization of the source and exploits precomputed GEF kernels
Using Fennoscandia as a test region, we show that real‐time 3‐D modeling of the GEF takes less than 0.025 s