| Project/Area Number |
10640415
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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 | HOKKAIDO UNIVERSITY |
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Principal Investigator |
XIE Shang-Ping Hokkaido University, Graduate School of Environmental Earth Science, Asso. Pro., 大学院・地球環境科学研究科, 助教授 (00261347)
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| Co-Investigator(Kenkyū-buntansha) |
SHIOTANI Masato okkaido University, Graduate School of Environmental Earth Science, Pro., 大学院・地球環境科学研究科, 教授 (50192604)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 1999: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1998: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | Intertropical convergence zone / Ocean-atmosphere interaction / Climate model / Wind-evaporation-sea surface temperature feedback / Atlantic dipole oscillation / Coupled ocean-atmosphere instability / Summer monsoon / Desert formation / 風速・蒸発 / 海面水温フィードバック / 熱帯気候の南北非対称性 / 大気・海洋相互作用 / 大循環モデル |
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| Research Abstract |
The northward departure of the Pacific intertropical convergencezone (ITCZ) is a long-standing mistery of tropical climate. We coupledan atmospheric general circulation model (CGM) with an ocean model of intermediate complexity to investigate the roles of continentalgeometry and ocean-atmosphere interaction in breaking the equatorial symmetry set by the annual-mean solar forcing. Basin-scale asymmetries in sea surface temperature and the ITCZ emege when an asymmetric feature is added to the continent on the eastern side of the ocean. By contrast, the coupled system remains symmetric when the same asymmetric continental feature is added onto the ocean western boundary. This result suggests that the American continents are more important in determining the asymmetric aspect of the Pacific climate than larger Eurasia.
Despite sharing many common climatological feature, the Pacific and Atlantic display temporal variability of very different spatial patterns. The analysis of a simple coupled ocean-atmosphere model suggests that the Pacific, with a larger zonal dimension, will be dominated by the symmetric El Nino mode while the smaller Atlantic is likely to see both the symmetric and anti-symmetric modes of climate variability, a result consistent with observations.
The Indian Ocean is unique among the tropical oceans, being dominated by strong seasonal monsoons. An atmospheric GCM is run under an idealized land-sea distribution, and its results reveal new aspects of summer monsoon dynamics that can explain its abrupt onset.
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