We observe auroral emissions from both space and ground, and combine them with satellites and ground-based radar to promote a comprehensive understanding of auroral physics.
Certain types of auroras are of interest because of the very high energy precipitating electrons that affect the middle atmosphere. We launched the LAMP rocket in 2022, the first in the world to successfully observe these phenomena simultaneously. We also plan to launch the LAMP-2 rocket.
On the other hand, the high-latitude polar cap region, which is directly affected by the solar wind, is attracting attention from the perspective of space weather. We have developed 10 all-sky cameras and constructed an observation network that covers a wide area over the Antarctic Continent.

‘Geospace’ is the space around the Earth that consist of plasma (charged particles) originating from the Earth’s atmosphere and the solar wind. The electromagnetic waves propagating in the plasma are called ‘plasma waves’. In space, collisions between particles rarely occur, but the motion of particles is scattered by ‘collisions’ between plasma waves and charged particles. As a result, the enegetic particles precipiatte into the Earth’s atmosphere and cause polar auroras and affect the composition in the upper atmosphere. Therefore, studying the generation and propagation of plasma waves is important topic for understanding the connection between space and the Earth’s atmosphere. Using observations of plasma waves by the Arase satellite and groundbased aurora observations, we are investigating how plasma waves propagate through geospace and scatter enegetic charged particles, and studying the effects of space on the Earth’s atmosphere.

“Have you heard that “Earth is like a giant magnet”? This magnet creates a vast region called the magnetosphere, which acts like a protective shield from the stream of charged particles known as the solar wind.

I study what’s going on inside this magnetosphere—especially what kinds of ions (electrically charged particles) are there, where they are, and how many of them exist by analyzing lectromagnetic ion cyclotron (EMIC) waves. Right now, I’m working with data from the Arase satellite to try to uncover the types and ratios of ions present in the magnetosphere.

This could also help us study other planets. For example, BepiColombo is scheduled to arrive at Mercury in 2026, and JUICE will begin orbiting Jupiter in 2031. By applying this method, we hope to open new ways to explore planetary magnetic fields and plasma environments across the solar system.”

Auroral Kilometric Radiation (AKR), a type of auroral radio emission from Earth, is closely associated with various phenomena and structures in the Earth’s magnetosphere. It serves as a valuable barometer for understanding the state and dynamics of the magnetosphere.

However, long-term statistical studies of AKR—particularly those focusing on its correlation with solar activity—have been limited.

In this study, I aim to conduct a long-term statistical analysis of AKR using data from the Geotail satellite, which has observed the Earth’s magnetosphere for nearly 30 years.

By clarifying the occurrence characteristics and temporal variations of AKR, I hope to contribute to a deeper understanding of the Earth’s magnetospheric environment.

Since 2017 the Arase satellite has been investigating electron number density and temperature in the near-Earth environment. Electron density is derived from the upper-hybrid resonance (UHR) frequency recorded by the onboard electric-field antennas, yet this technique tends to underestimate density in low-density regions. To address the bias, we integrated satellite potential, in-situ particle measurements, and solar UV flux, and compared the resulting data set for 2017–2022. The analysis shows that, under geomagnetically quiet conditions, satellite potential and electron density exhibit a clear proportional relationship, with an additional dependence on electron temperature. These findings reduce measurement uncertainties and will enhance the accuracy of plasma observations by BepiColombo/MMO, scheduled to explore Mercury in 2026.