| Project/Area Number |
14540404
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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 | Tokyo University |
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Principal Investigator |
ABE Ayako University of Tokyo, CCSR, Assistant Professor, 気候システム研究センター, 助教授 (30272537)
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| Co-Investigator(Kenkyū-buntansha) |
TAJIKA Eiichi University of Tokyo, Department of Earth and Planetary Science, Associate Professor, 大学院理工学研究科地球惑星科学専攻, 助教授 (70251410)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 2003: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2002: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Paleoclimate / General Circulation Model (GCM) / Snowball Earth condition / Paleoclimate modelling / Carbon Cycle / Climate Sensitivity / Proterozoic / 気候 / 氷床 / 大循環モデル |
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| Research Abstract |
The critical condition which leads to "snowball earth" which occurred in the Proterozoic in the past is investigated by searching the response of the earth to solar constant and CO2 change systematically using Atmospheric General Circulation Model (AGCM) coupled with a slab ocean (50m depth water). The role of seasonality as well as that of continental distribution is discussed.
The system is under the partially ice covered condition (some ice on the earth and open ocean exists) for a broad range of external forcing, ex. 15 per cent of present solar constant and is consistent with other GCM studies. The response of AGCM to external forcing is quite different from that of EBM (energy balance models) in case the ice edge locates at mid to low latitude, preventing the system from falling into snowball condition. The reason for the persistent ice edge of AGCM compared to conventional EBM is partly due to the role of latent heat transport and also the seasonality. The dependence of heat transport of AGCM to external forcing is not as expected as that from that of diffusion type, and it is influenced by the seasonality of sea ice.
By testing three continental distributions including the present-day geography, it is suggested that the continental distribution does not modify the structure of the climate sensitivity, i.e., the dependence of ice edge to solar constant under fixed atmospheric CO2 content. The possibility that the continental distribution influences the ocean heat transport and the water vapour transport through monsoon circulation which affects the atmospheric CO2 amount through erosion process should be examined in detail for the future study.
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