[P-EM08] Space Weather and Space Climate

[PEM08-P29] Geomagnetically induced currents observed around solar minimum of Cycle 24

*Shinichi Watari¹, Satoko Nakamura², Yusuke Ebihara³, Aoi Nakamizo¹ (1.National Institute of Information and Communications Technology, 2.Institute for Space-Earth Environmental Research, Nagoya University, 3.Research Institute for Sustainable Humanosphere, Kyoto University)

Keywords:Geomagnetically Induced Current (GIC), geomagnetic storm, Sudden Storm Commencement (SSC), Sudden Impulse (SI), bay disturbance, Solar Flare Effect (SFE)

We started to install our equipment to substations around Kanto area and to measure geomagnetic induced currents (GICs) by the KAKENHI project (PSTEP) since the end of February 2017. Geomagnetic storms with Dst less than -100 nT occurred only three times during this periods because of solar minimum of Cycle 24. GICs were relatively often observed associated with bay disturbances, which were caused by aurora activities at high latitudes although GICs associated with SSCs or SIs were also observed. A GIC was observed associated with a geomagnetic disturbance by M4.4 flare on 1 April 2017. The geomagnetic disturbance caused by a solar flare is called Solar Flare Effect (SFE). This SFE was not an intense event. Kakioka magnetic observatory reported a SFE with a maximum variation of geomagnetic horizontal component of -67 nT on 15 November 1960. The maximum value of time derivative of this event was approximately -20 nT/min. We will report the analysis of these events using GIC observations of neighboring substations.

After solar minimum in December 2019, solar activities gradually increases and large flares and intense geomagnetic storms are expected. We will continue the GIC measurements and have a plan to utilize the result of the simulation of the Earth’s magnetosphere for the estimation of GICs.