16:15 〜 16:30
[PAE18-22] Simulating the effects of salinity on ocean planet climates with 3D AOGCM
キーワード：系外惑星、ハビタビリティ、全球気候モデル、海洋循環
Terrestrial exoplanets around M dwarfs are the important targets for current observations as they are the least difficult planets to detect and characterize. According to the studies of planet formation, these exoplanets could sustain large amounts of surface water. Due to closer orbits and tidal forces by the host star, these planets would be tidally-locked and fully covered by oceans on a planetary surface, unlike Earth.
On the other hand, Earth’s ocean circulation largely affects the climate (e.g. meridional heat transport, water cycle, storing substances). In addition, meridional overturning circulation on Earth is driven by density differences, which are affected by sea water temperature and salinity, resulting from heat exchange to atmosphere and salinity change by precipitation or sea ice formation. Although salinity has large influences on ocean behavior, such as the strength of ocean circulation and the condition of sea ice formation, this effect on tidally-locked ocean planets has been still unknown.
To investigate the salinity influence on global ocean circulation, we developed an atmospheric and oceanic global climate model (AOGCM) for exoplanets based on MIROC, originally developed for current Earth climate simulations. Then, we simulated climates of tidally-locked ocean planets with 1 Earth ocean mass and Earth-like/zero salinity. Comparing the results of between Earth-like salinity and zero salinity (pure water), we found that salinity affects not only sea ice distribution due to freezing-point depression, but also intensity of meridional and zonal ocean current. In this presentation, we will show the climatic behavior and physical mechanisms of these differences by salinity.
On the other hand, Earth’s ocean circulation largely affects the climate (e.g. meridional heat transport, water cycle, storing substances). In addition, meridional overturning circulation on Earth is driven by density differences, which are affected by sea water temperature and salinity, resulting from heat exchange to atmosphere and salinity change by precipitation or sea ice formation. Although salinity has large influences on ocean behavior, such as the strength of ocean circulation and the condition of sea ice formation, this effect on tidally-locked ocean planets has been still unknown.
To investigate the salinity influence on global ocean circulation, we developed an atmospheric and oceanic global climate model (AOGCM) for exoplanets based on MIROC, originally developed for current Earth climate simulations. Then, we simulated climates of tidally-locked ocean planets with 1 Earth ocean mass and Earth-like/zero salinity. Comparing the results of between Earth-like salinity and zero salinity (pure water), we found that salinity affects not only sea ice distribution due to freezing-point depression, but also intensity of meridional and zonal ocean current. In this presentation, we will show the climatic behavior and physical mechanisms of these differences by salinity.