Rigorous 3-D modeling of the ground electric field in Fennoscandia
during the Halloween geomagnetic storm
Abstract
In this study, we perform rigorous three-dimensional (3-D) ground
electric field (GEF) modeling in Fennoscandia for three days of the
Halloween geomagnetic storm (29-31 October 2003) using magnetic field
data from the IMAGE magnetometer network and a 3-D conductivity model of
the region. To explore the influence of the inducing source model on 3-D GEF simulations, we consider three different approaches to source approximation. Within the first two approaches, the source
varies laterally, whereas in the third method, the GEF is calculated by
implementing the time-domain realization of the magnetotelluric
intersite impedance method. We then compare GEF-based geomagnetically
induced current (GIC) with observations at the Mäntsälä natural gas
pipeline recording point. We conclude that a high correlation between
modeled and recorded GIC is observed for all considered approaches. The
highest correlation is achieved when performing a 3-D GEF simulation
using a “conductivity-based” laterally nonuniform inducing source. Our
results also highlight the strong dependence of the GEF on the earth’s
conductivity distribution.