Real-time 3-D modeling of the ground electric field due to space weather
events. A concept and its validation
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
and time series of respective expansion coefficients and exploits
precomputed frequency-domain GEF generated by corresponding spatial
modes. 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 IMAGE 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 x 512 grid requires less
than 0.025 seconds provided that frequency-domain GEF due to
pre-selected spatial modes 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.