Dr. Yuichi Otsuka
Nagoya University, Japan
Airglow and GPS observations of ionospheric disturbances: Activity of Nagoya University
Solar-Terrestrial Environment Laboratory, Nagoya University in Japan is operating 12 all-sky airglow imagers in the world in order to investigate the dynamics of the Earth's ionosphere through nocturnal airglow emissions. The airglow imaging observations revealed wavy structures of the ionospheric plasma density at mid-latitudes and we found that the wavy structures are mirrored in both hemispheres connecting the geomagnetic fields. Global Positioning System (GPS) is also used for the ionospheric study. From delay and advance of the GPS radio propagation, total electron content (TEC), that is an integration of the ionospheric plasma density along the ray path of the radio wave, can be measured. Using more than 1,200 GPS receivers in Japan, we observed TEC variations approximately 7 minutes after the 2011 Tohoku Earthquake. The TEC variations reached North America 9 hours after the earthquake.