2021 Fiscal Year Final Research Report
Global Ocean Circulation Controlled by Hemispherically Asymmetric Distribution of Seawater Temperature and Nonlinear Equation of State
Project/Area Number |
19K03974
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Research Category |
Grant-in-Aid for Scientific Research (C)
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Allocation Type | Multi-year Fund |
Section | 一般 |
Review Section |
Basic Section 17020:Atmospheric and hydrospheric sciences-related
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Research Institution | Kyoto University |
Principal Investigator |
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Project Period (FY) |
2019-04-01 – 2022-03-31
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Keywords | 地球規模海洋循環 / 非線形状態方程式 / 水温の南北非対称分布 / 南極周極流 |
Outline of Final Research Achievements |
Numerical experiments with an idealized model ocean reveal that difference of water temperature (salinity) between both polar oceans can strengthen a sinking around Antarctica by the action of the nonlinear equation of state (EOS) for sea water such as cabbeling and thermobaricity. North Atlantic Deep Water (NADW) which is formed in the northern Atlantic travels southward in the deep layer and upwells to meet the surface water around Antarctica. Their mixture becomes denser than the parent waters by the action of nonlinear EOS since NADW is warmer (saltier) than the surface water around Antarctica. The denser water partly sinks to the sea bottom to constitute Antarctic Bottom Water (AABW). Additional experiments suggest that the process may be an important factor to control the general ocean circulation.
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Free Research Field |
海洋物理学
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Academic Significance and Societal Importance of the Research Achievements |
地球規模の海洋循環の形成と変動に大西洋における水温(塩分)の南北非対称性が重要な役割を果たしている可能性が本研究により初めて示された。この過程には大気圧下での真水が約4℃で最も重くなるのと同じ分子レベルでの性質(状態方程式の非線形性)が本質的な役割を果たしており、ミクロスケールから地球規模に至る海洋循環の新たな側面が明らかになった。得られた成果は現在の地球気候に限らず、地質データに見られる過去の気候の理解、地球温暖化に起因する将来の予測に大きく寄与することが期待される。
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