ALBERT

Description: Magneto-impedance (MI) effect was discovered about 30 years ago and a micro-size magnetic sensor that utilizes this effect becomes commercially available. Nosé et al. (2022, doi: 10.1029/2022JA030809) made some modifications to the commercially available MI sensors to cover the dynamic range of the geomagnetic field. For the period of March 30 to April 27, 2018, they conducted experimental observations of geomagnetic field variations with the MI sensors at the Mineyama observatory in Japan. Data obtained with the MI sensors are compared with those from the fluxgate magnetometer (FGM) that has been working at the observatory. Results showed that the MI sensors can record geomagnetic field variations such as geomagnetic storms, Sq variations, low-latitude positive bays, SSC, and geomagnetic pulsations with a peak-to-peak amplitude of £ 1 nT that are also detected with the FGM. This study revealed that the MI sensor can measure the geomagnetic field variations in a period from a few tens of seconds to a few hours. Using MI sensors, Raspberry Pi, low-cost 24-bit A/D converters, and stable power supply circuits, we developed a magnetometer with approximately $4,000, which is named MIM-Pi (MI sensor Magnetometer with Raspberry Pi). Because of its low cost, MIM-Pi provides an opportunity to construct a dense observation network of geomagnetic field. We are now deploying MIM-Pi in Kanto-Tohoku area. When we apply the magnetoseismology method to the data from such dense observation network, it will be possible to monitor fine structures of the plasma mass density distribution in the inner magnetosphere.