The Solar-Terrestrial Environment and Climate Unit aims to deepen our understanding of the Sun, its surrounding environment, and their impacts on Earth’s climate and weather.
The timescales of solar variations range from one month to a few thousand years. Observational records show that climate and meteorological phenomena respond to such periodic variations in solar activity; however, the mechanisms underlying this connection remain unresolved. There are several possible pathways through which solar variability may influence Earth's climate. Among these, we are particularly interested in the effects of galactic cosmic rays. Galactic cosmic rays are charged particles originating from outside the heliosphere, and their intensity is modulated by the solar-wind magnetic field, which reaches beyond the solar system. Cosmic rays are a major source of ionization in the atmosphere. Ions are known to promote the formation of new aerosol particles from gaseous compounds, including those emitted by forests and marine ecosystems. Some of these particles grow into cloud condensation nuclei and influence cloud properties.
Using observational data and model experiments, we investigate how ions influence clouds through new particle formation and how changes in cloud properties affect atmospheric and oceanic circulation. Our interests also include the effects of these processes on extreme weather events such as typhoons and thunderstorms.
Through this research, we aim to achieve a comprehensive understanding of the Earth as a system open to the nearby space environment.
