Japan Geoscience Union Meeting 2019

Presentation information

[E] Oral

P (Space and Planetary Sciences ) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM12] Space Weather and Space Climate

Mon. May 27, 2019 1:45 PM - 3:15 PM A04 (TOKYO BAY MAKUHARI HALL)

convener:Ryuho Kataoka(National Institute of Polar Research), Antti A Pulkkinen(NASA Goddard Space Flight Center), Kanya Kusano(Institute for Space-Earth Environmental Research, Nagoya University), Kaori Sakaguchi(National Institute of Information and Communications Technology), Chairperson:Antti Pulkkinen(NASA/GSFC)

2:30 PM - 2:45 PM

[PEM12-16] Simulation of Geomagnetically Induced Current (GIC) Flowing in 500 kV Power Grid in Japan Including a Three-Dimensional Ground Inhomogeneity

*Satoko Nakamura1, Yusuke Ebihara1, Shigeru Fujita2, Tada-nori Goto3, Shinichi Watari4 (1.Research Institute for Sustainable Humanosphere, Kyoto University., 2.Meteorological College, Japan Meteorological Agency, 3.Graduate School of Engineering, Kyoto University, 4.National Institute of Information and Communications Technology)

We evaluate geomagnetically induced currents (GICs) flowing in the Japanese power grid during severe space weather by using several methods. First, the three-dimensional distribution of the geomagnetically induced electric field (GIE) was calculated by using the 3D finite-difference time-domain (FDTD) method with a three-dimensional electrical conductivity model constructed from a global relief model and a global map of sediment thickness. To simulate a time evolution of magnetic storms, the sheet current with its intensity inferred from the ground magnetic disturbance for famous magnetic storms is imposed. We compared the calculated GICs with the observed ones at substations around Tokyo, and found a certain agreement when the uneven distribution of GIE is incorporated with the simulation. The simulation result shows that GIE exhibits localized, uneven distribution that can be attributed to charge accumulation due to the inhomogeneous conductivity below the Earth's surface. The charge accumulation becomes large when the conductivity gradient vector is parallel, or anti-parallel to the incident electric field. For given GIE, we calculated the GICs flowing in a simplified 500 kV power grid network in Japan. The influence of the inhomogeneous ground conductivity on GIC appears to depend on a combination of the location of substations and the direction of the source current. Second, we assume conductivity anomaly simulating a plate boundary to test the effect of large-scale underground structure on GICs. We find that these structures may strongly enhance GIC just above them. Finally, we derive transfer functions between the GIC observation at 4 substations in Japan and geomagnetic field recorded at the Kakioka station. The transfer functions are not always applicable for Japanese GIC. We will discuss the validity of the assumption of uniform ground and influence of the time variation of earthing resistance of substations.