A study of turbulence in the tidally-induced bottom boundary layer focusing on the horizontal component of Earth rotation and diurnal sea-surface heating
| Project/Area Number |
16K05554
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Meteorology/Physical oceanography/Hydrology
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000)
Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2017: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2016: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
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| Keywords | 潮流 / 海底境界層 / 自転ベクトル / DNSモデル / 加熱 / 自転ベクトルの水平成分 / 緯度依存性 / 海洋物理学 / 潮流海底境界層 / 日周加熱 / コリオリ効果 / DNS実験 |
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| Outline of Final Research Achievements |
Turbulent properties of the tidally-induced bottom bundary layer are largely affected by the horizontal component of Earth rotation, fc. At low latitudes, specially, the boundary layer is thickened by a factor of 1.3-2.0 on the tidal average, and the apparent diffusivity is enhanced by a factor of 1.7-2.8. It should be noted that such enhancement never appears in the turbulent kinetic energy and friction velocity. Diurnal heating, on the other hand, tends to suppress development of the bundary layer probably because it can cause effective downward heat transport above the boundary layer. These results indicate that fc and diurnal heating are taken into account as well as a tidal amplitude and period, and the traditional Coriolis parameter for a more sophisticated parameterization of tidal mixings.
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| Academic Significance and Societal Importance of the Research Achievements |
潮流は人の社会活動に深く関わる沿岸海域の主要な流れであり、漁業、環境問題を考える上で最も重要な物理過程の一つである。潮流によって海底付近に形成される乱流境界層は海水を鉛直に混合する重要な役割を果たすが、これまで十分に検討されていない地球自転の水平成分と加熱の日周変化の効果に注目して、その特性を数値モデル実験により初めて明らかにした。本研究の成果は、沿岸海況を正確に予測するためのシミュレーションモデルの開発と精度向上に向けた基盤的知見として重要である。
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Report
(4 results)
Research Products
(1 results)
