Geomagnetically induced currents at equator caused by interplanetary structures

Abstract

The rapid changes in the Geomagnetic field induce electric fields at the conducting surface of Earth, which can cause strong electrical currents, known as Geomagnetically Induced Currents (GICs), that flow through the long conducting structures like electric power transmission lines, long pipelines on the ground. The elevated GICs are most popularly known during severe geomagnetic storms at high latitudes. However, this study reports cases of strong GICs at the geomagnetic equator due to various interplanetary structures in the solar wind. The horizontal component at the equatorial stations recorded a peak change in magnetic field exhibiting a larger value than the concerning value of 100 nT/min, which is a risk factor to the electric power systems. The responsible physical mechanisms for these sudden changes in the horizontal component at the equatorial stations were examined through magneto-hydrodynamic model simulations. These results provide new understandings on the extent of extreme changes in the equatorial region can be caused by interplanetary structures, which can have potential impacts on electric power grid systems.