Geoelectric and geomagnetic response to the oscillating magnetospheric current in Japan and Korea

Abstract:

We calculate the electric field induced in the ground with the three-dimensional heterogeneous distribution of the resistivity by the oscillating magnetospheric current. The ground resistivity is given from the specific resistivity values of the sea water layer, the sediment layer, and the rock layer as 0.33Ohm m, 10Ohm m, and 1000Ohm m, respectively, according to the global relief model of land topography and bathymetry as well as from the global sediment map. The oscillation has the period including the ULF range. This calculation is important for evaluation of the extreme value of the geomagnetically induced current for the extreme severe space weather event. The calculation indicates that, in the countries with coastlines like Japan and Korea, the coastline effect plays an essential role in induction of the electric field. As a result, the enhanced electric field intensity will appear when the induced current in the sea water region flows almost perpendicular to the coast line with a steep slope. The eastern coast of Korean Peninsula, the western coast of the northern Honshu Island, and the western part of Niigata Prefecture (central part of the western coast of the Honshu Island) are included in this category. In addition, the bay with deep bathymetry and wide mouth tends to have much enhanced electric field intensity in the throat of the bay when the induced current is parallel to the axis of the bay. This information is important when we prepare the GIC disaster for the extremely severe space weather event. Furthermore, we present the geomagnetic effect due to the current induced in the ground with the three-dimensional heterogeneous resistivity. This information is useful for ground geomagnetic observations.