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Research Topics

Atmosphere and ocean play important roles in determining the surface environments of the Earth and many of the other planets. For example, mean surface temperature of the present Earth is about 15 degrees C and is maintained by the greenhouse effect of the atmosphere and the meridional heat transport due to circulations of the atmosphere and the oceans. Surface environment is expected to change when the atmospheric composition and/or the circulations of the atmosphere and the ocean are varied. However, the mechanisms governing the surface environment are not fully understood, and therefore it remains difficult to assess possible changes. It is remarkable that Earth’s surface environment has remained habitable for life for 4.5 billion years, despite occasional freezing events. We aim to understand the principles governing the climate systems and various phenomena in planetary atmospheres and oceans.

Planetary meteorology and climatology

The atmospheric dynamics of Mars and Venus are quite different from those of Earth. For example, in the Venusian atmosphere, high-speed wind, so-called superrotation, circulates around the planet in a direction of the planetary rotation in 4 to 5 Earth days. In the Martian atmosphere, dust storms of various scales, from regional to global, occur frequently. Furthermore, the surface environment and circulation of exoplanets would be significantly different from those in our solar system. Through theoretical modeling and numerical simulations, we hope to elucidate the mechanisms controlling atmospheric dynamics and predict atmospheric circulation on exoplanets.

Formation and evolution of habitable planet

The Earth’s surface is temperate and habitable, but its neighboring planets, Venus and Mars, are either too hot or too cold for life. Differences in the surface environment are determined by factors such as the intensity of solar radiative heating, the mass and composition of the atmosphere, the planet’s rotation rate and axial tilt, etc. Planetary atmosphere is formed simultaneously with planet formation, and after formation, its mass and composition change as the atmospheric components escape into space and exchange materials with the solid planet. Understanding the diversity of planetary surface environments requires understanding the evolution of atmospheric mass and composition from planet formation through subsequent geological timescales. We aim to elucidate the principles that govern the formation and evolution of planetary surface environments using methods such as theory (mathematical and physical descriptions of phenomena), numerical experiments (simplified planetary surface environment models), and observations (space probes and ground-based telescopes).

Current Projects:

  • General Circulation Models for various planetary atmospheres (Mars, Earth, Venus, outer planets, exoplanets)
  • Simplified models of surface environment on terrestrial planets
  • Data analyses of the Venus Climate Orbiter/Akatsuki’s observational data
  • Development of meteorological instruments for Mars lander