[P-EM09] Space Weather and Space Climate

[PEM09-P22] Seasonal and diurnal variations observed in Geomagnetically Induced Current (GIC) in the Kanto region, Japan

*出井 駿¹、三好 由純¹、中村 紗都子¹、海老原 祐輔²、亘 慎一³ (1.名古屋大学宇宙地球環境研究所、2.京都大学生存圏研究所、3.情報通信研究機構)

キーワード：地磁気誘導電流

Geomagnetically Induced Current (GIC) is a phenomenon in which quasi-direct current flows through earthing conductors such as power grids and communication cables, driven by geomagnetic disturbances. Many cases of GIC with several hundred amps have been reported during strong magnetic storms. Such strong GICs pose a risk to power grids damage due to malfunctions of protective relays and insulation degradation resulting from hot spot heating. These severe cases of GIC have been reported at high magnetic latitudes (auroral latitudes). Based on statistical studies, the risk of GIC in power systems outside the high latitudes had been considered insignificant. Thus, the risk of GICs has not been studied in middle- and low- latitude regions such as Japan, especially in observations. Recently, recent studies have shown that significant GICs can also occur in middle and low latitude regions during huge magnetic storms. In addition, there are reports that small GICs may also cause a reduction in energy efficiency. GIC observations have been initiated in these regions as well. Our study focuses on the GICs measured at the STB substation in Japan. Our statistical analysis of the observed data shows that the GICs are dependent on the magnetic disturbance and has seasonal and diurnal variations.