| 摘要: |
| 为了解南海北部陆坡区的内部混合过程, 2004年4月30日至5月1日,“延平2号”科考船在该海域利用自由沉降式的微结构剖面仪TurboMAP-Ⅱ进行了一次混合过程的直接观测。观测海区南海次表层水团和南海中层水团形成的特定温盐结构, 使得150～500 m之间出现盐指现象。通过对观测数据的处理和分析, 研究了观测海区的湍动能耗散率、热耗散率和热扩散系数的分布以及盐指现象对混合效率的影响。观测海区的湍动能耗散率为2.0×10-10～7.8×10-7W/ kg , 最大值出现在上混合层; 热耗散率为2.7×10-9～1.5×10-6℃2/s, 最大值出现在温跃层附近。层结稳定区混合效率的平均值为0.18, 与常用值0.2 非常接近, 盐指发生区混合效率的平均值为0.76, 表明盐指现象的存在提高了混合效率。 |
| 关键词: 南海北部陆坡区 盐指 湍动能耗散率 热耗散率 混合效率 |
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| 基金项目:国家自然科学基金项目( 40552002) |
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| Observation of mixing processes over the continental slope of the northern South China Sea |
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| Abstract: |
| An observation was conducted on board R/V Yan Ping 2 from April 30 to May 1, 2004. The small-scale process over the continental slope of the northern South China Sea ( SCS) was studied from the direct microstructure observation using a free-falling instrument TurboMAP-II(Turbulence Ocean Microst ructures Acquisition Profiler). Due to the presentation of the South China Sea subsurface water and the South China Sea intermediate water, the salt fingering is expected to occur between 150 m and 500 m. The result sreveal that the dissipation rate of turbulent kinetic energy (TKE) in this region ranges from 2.0×10-10～7.8×10-7W/kg, with the maximum existing in the surface mixing layer; the dissipation rate of thermal variance ranges from 2.7×10-9～1.5×10-6℃2/s, with the max imum located around the thermocline. Besides, the mean value of the mixing efficiency is 0.18 in the doubly stable layers, very close to the value of 0.2 used in earlier litrerature. But in the finger-favorable layers, it’s about 0. 76 much larger than that in the doubly stable layers, showing that the salt fingering makes a significant contribution to the mixing efficiency increasing. |
| Key words: Northern South China Sea salt finger the dissipation rate of turbulent kinetic energy( TKE) the dissipation rate of thermal variance mixing efficiency |
