Geoinduced currents on Karelian-Kola power line and finnish gas pipeline on september, 12–13 2017

Abstract

Geomagnetic activity and occurrence of large values of geoinduced currents (GICs) during a moderate magnetic storm (SYM/H ∼ −65 nT) on September, 12–13 2017 have been studied. Two intense substorms (AL ∼600 nT and ∼1200 nT) were observed within the period of this magnetic storm. Amplification and motion of electrojets during substorms is known to be one of the important sources of GIC value increase in the auroral zone. The fine spatial temporal structure of westward electrojet has been analyzed using the latitudinal profiles of the IMAGE network and the equivalent currents of the MIRACLE system data. GICs activity were monitored by EURISGIC from Russian stations Vykhodnoy (VKH) and Revda (RVD) in the North-West of Russia (eurisgic.ru) and Mäntsälä station (MAN) in South Finland. The data from these stations are convenient to track GIC from ∼60° to ∼69° geographical latitudes. It has been shown that the increase in GIC amplitudes at different latitudes was associated with the poleward movement of the westward electrojet during the expansion phase of the substorm. Besides, it has been found that the source of the GICs at the recovery phase of the second substorm appeared to be a short pulse of Pc5 pulsations and the amplitudes of GICs were comparable with substorms one. It is also shown that the increase in GIC amplitude are in good agreement with the increase in the Wp- and IL-geomagnetic indices used for global and local control over the substorm appearance.