Modeling study of the physical and chemical processes of Martian atmosphere connecting from the surface to thermosphere and approaching to the climate change

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K05552
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: Tohoku University (2019); National Institute of Information and Communications Technology (2016-2018)
• Principal Investigator: Kuroda Takeshi 東北大学, 理学研究科, 助教 (40613394)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 火星 / 大気大循環モデル / 大気物質循環 / 古気候 / 大気重力波

Outline of Final Research Achievements

Using a Mars general circulation model (MGCM) with the horizontal resolution of ~1.1 degrees, we investigated the generation and propagation (up to ~80 km of the model top) of gravity waves, and the effects of them on the atmospheric temperature and wind fields, including the dependency of horizontal wavenumbers and seasonal changes. Also, we investigated the dependency of horizontal resolution of the MGCM on the simulated water cycle (including HDO/H2O isotopic fractionations) and polar-night CO2 snowfalls in the lower atmosphere, for the connections with the processes of upper atmosphere and atmospheric escape of which the observational investigations by the spacecrafts have significantly progressed recently. Moreover, we made the GCM simulations of paleo-Mars climate in ~3.8 Ga, and indicated the possibility of a 'cool and wet' climate at that time which repeated the rainfall and snowfall seasonally in the equatorial regions.

Free Research Field

惑星気象学

Academic Significance and Societal Importance of the Research Achievements

形成初期の液体の海が地表に存在したと考えられる状態から不可逆的に水を失った火星の気候変動過程に迫るべく、現在の火星下層大気における大気重力波の励起及び上層大気への伝播とそれらを考慮した精緻な水・物質循環を高分解能全球大気モデルを用いて再現し、熱圏での大気散逸過程に与える力学的・化学的な影響を調べた。合わせて初期火星の気候も全球大気モデルで推測し、観測されている事実と照合し妥当性を議論することで火星の気候変遷とそのメカニズムについて新しい理論的な示唆を与えた。