| Project/Area Number |
16540395
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Meteorology/Physical oceanography/Hydrology
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| Research Institution | The University of Tokyo |
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Principal Investigator |
ABE Yutaka The University of Tokyo, Department of Earth and Planetary science, Graduate school of science, Associate Professor, 大学院・理学系研究科, 助教授 (90192468)
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| Co-Investigator(Kenkyū-buntansha) |
ABE-OUCHI Ayako The University of Tokyo, Center for climate system research, Associate Professor, 気候システム研究センター, 助教授 (30272537)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2005: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2004: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | runaway greenhouse / water vapor feedback / aqua planet / land planet / habitability / water / climatology / planetary science / 多重平衡状態 / 太陽放射の増大 |
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| Research Abstract |
Most of the previous studies on the habitable zone implicitly assume an ocean-covered 'aqua' planet that has a large amount of liquid water like the present Earth. However, there is a possibility of a habitable 'land' planet that is covered by vast dry desert but has locally abundant water. The conditions for the existence of liquid water can be different for a less water land planet from that of an aqua planet, because, both the ice-albedo feedback, which causes the complete freezing, and the runaway greenhouse, which causes the complete evaporation, are caused by the phase change of water. 1. We performed experiments using a general circulation model CCSR/NIES AGCM5.4g and determined the minimum solar flux that cause the complete evaporation of water from the surface. 2. If the distribution of the ground water is completely controlled by the atmospheric circulation, the ground water is localized in high latitude area. Then, the liquid water exists on the surface beyond the critical flux of the runaway greenhouse. 3. We found multiple equilibrium states. 4. Vapor abundance in the stratosphere is kept very low while water exists on the surface. Thus, this state is very stable against the atmospheric escape. 5. Water abundance which is too large will not allow the atmospheric control of water distribution. Then, the stability of liquid water is limited by that of an aqua planet. This suggests, against the intuition, that the stable range of liquid water is wider for less water "land" planets than water abundant "aqua" planets.
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