| 南极西北威德尔海上层海洋湍流混合研究 |
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| 引用本文： | 郭桂军,史久新,矫玉田.南极西北威德尔海上层海洋湍流混合研究[J].海洋学报(英文版),2016,35(3):1-9. |
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| 作者姓名： | 郭桂军 史久新 矫玉田 |
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| 作者单位： | 中国海洋大学教育部物理海洋重点实验室, 山东青岛 266003;中国海洋大学海洋与大气学院, 山东青岛 266100,中国海洋大学教育部物理海洋重点实验室, 山东青岛 266003;中国海洋大学海洋与大气学院, 山东青岛 266100,中国海洋大学教育部物理海洋重点实验室, 山东青岛 266003 |
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| 摘 要： | Turbulent mixing in the upper ocean(30-200 m) of the northwestern Weddell Sea is investigated based on profiles of temperature,salinity and microstructure data obtained during February 2014.Vertical thermohaline structures are distinct due to geographic features and sea ice distribution,resulting in that turbulent dissipation rates(ε) and turbulent diffusivity(K) are vertically and spatially non-uniform.On the shelf north of Antarctic Peninsula and Philip Ridge,with a relatively homogeneous vertical structure of temperature and salinity through the entire water column in the upper 200 m,both ε and K show significantly enhanced values in the order of O(10~(-7))-O(10~(-6)) W/kg and O(10~(-3))-O(10~(-2)) m~2/s respectively,about two or three orders of magnitude higher than those in the open ocean.Mixing intensities tend to be mild due to strong stratification in the Powell Basin and South Orkney Plateau,where s decreases with depth from O(10~(-8)) to O(10~(-9)) W/kg,while K changes vertically in an inverse direction relative to s from O(10~(-6)) to O(10~(-5)) m~2/s.In the marginal ice zone,K is vertically stable with the order of10~(-4) m~2/s although both intense dissipation and strong stratification occur at depth of 50-100 m below a cold freshened mixed layer.Though previous studies indentify wind work and tides as the primary energy sources for turbulent mixing in coastal regions,our results indicate weak relationship between K and wind stress or tidal kinetic energy.Instead,intensified mixing occurs with large bottom roughness,demonstrating that only when internal waves generated by wind and tide impinge on steep topography can the energy dissipate to support mixing.In addition,geostrophic current flowing out of the Weddell Sea through the gap west of Philip Passage is another energy source contributing to the local intense mixing.
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| 关 键 词： | 混合 湍动能耗散率 湍扩散率 上层海洋 威德尔海 |
| 收稿时间： | 2015/9/10 0:00:00 |
| 修稿时间： | 2015/11/9 0:00:00 |
Turbulent mixing in the upper ocean of the northwestern Weddell Sea, Antarctica |
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| GUO Guijun,SHI Jiuxin and JIAO Yutian.Turbulent mixing in the upper ocean of the northwestern Weddell Sea, Antarctica[J].Acta Oceanologica Sinica,2016,35(3):1-9. |
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| Authors: | GUO Guijun SHI Jiuxin and JIAO Yutian |
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| Institution: | 1.Key Laboratory of Physical Oceanography, Ocean University of China, Qingdao 266003, China;College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao 266100, China2.Key Laboratory of Physical Oceanography, Ocean University of China, Qingdao 266003, China |
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| Abstract: | Turbulent mixing in the upper ocean (30–200 m) of the northwestern Weddell Sea is investigated based on profiles of temperature, salinity and microstructure data obtained during February 2014. Vertical thermohaline structures are distinct due to geographic features and sea ice distribution, resulting in that turbulent dissipation rates (ε) and turbulent diffusivity (K) are vertically and spatially non-uniform. On the shelf north of Antarctic Peninsula and Philip Ridge, with a relatively homogeneous vertical structure of temperature and salinity through the entire water column in the upper 200 m, both ε and K show significantly enhanced values in the order of O(10–7)–O(10–6) W/kg and O(10–3)–O(10–2) m2/s respectively, about two or three orders of magnitude higher than those in the open ocean. Mixing intensities tend to be mild due to strong stratification in the Powell Basin and South Orkney Plateau, where ε decreases with depth from O(10–8) to O(10–9) W/kg, while K changes vertically in an inverse direction relative to ε from O(10–6) to O(10–5) m2/s. In the marginal ice zone, K is vertically stable with the order of 10–4 m2/s although both intense dissipation and strong stratification occur at depth of 50–100 m below a cold freshened mixed layer. Though previous studies indentify wind work and tides as the primary energy sources for turbulent mixing in coastal regions, our results indicate weak relationship between K and wind stress or tidal kinetic energy. Instead, intensified mixing occurs with large bottom roughness, demonstrating that only when internal waves generated by wind and tide impinge on steep topography can the energy dissipate to support mixing. In addition, geostrophic current flowing out of the Weddell Sea through the gap west of Philip Passage is another energy source contributing to the local intense mixing. |
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| Keywords: | mixing dissipation rate turbulent diffusivity upper ocean Weddell Sea |
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