Auroras, the most majestic and beautiful phenomenon in the polar region, remain puzzling and of great interest to researchers. An aurora is excited by electrons and protons precipitating from space near the Earth (geospace) to the polar atmosphere along the geomagnetic field lines and reflects variations in the geospace environment, which changes dynamically due to interaction between the solar wind, the magnetosphere and the ionosphere.

We have been conducting ground-based network observations in the Antarctic and Arctic regions with radars, magnetometers, and auroral imagers. Such observational data are used to study the mechanisms of various auroral phenomena and solar wind-magnetosphere-ionosphere coupling.

Aurora observed above Iceland, which is the geomagnetic conjugate point of Syowa Station

p>The transient region between the middle (10-100 km) and the upper (100 km -) atmosphere is a boundary region between space and the Earth. The upper atmosphere is partially ionized and acts as plasma particles, whereas conditions are more like fluid and neutral in the middle atmosphere. In contrast to the aurora in the upper atmosphere, notable phenomena in the polar middle atmosphere are an ozone hole, polar stratospheric clouds (PSC) and polar mesospheric clouds (PMC). In order to precisely measure the polar middle and upper atmosphere, which varies in response to meteorological disturbance from below, solar activities from above, and global meridional circulations of the atmosphere, we are carrying out various ground-based measurements in the Arctic and the Antarctic regions.

Polar mesospheric cloud (PMC) observed at Syowa Station - Photo by Y. Takeda (JARE50)