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热带海洋学报

• • 上一篇    

南海东北部深层次的细结构观测与湍流混合研究

朱小宇, 杨华, 毛蓓蓓, 郑雨轩   

  1. 中国海洋大学, 山东 青岛 266000

  • 收稿日期:2024-10-23 修回日期:2025-02-10 接受日期:2025-03-03
  • 通讯作者: 杨华
  • 基金资助:
    国家自然科学基金项目(61871354，6172780176)

Microstructure observations and turbulent mixing characteristics in the South China Sea

ZHU Xiaoyu YANG Hua MAO Beibei   ZHENG Yuxuan   

  1. Ocean University of China, Qingdao 266000, China

  • Received:2024-10-23 Revised:2025-02-10 Accepted:2025-03-03
  • Supported by:
    National Natural Science Foundation of China (61871354，6172780176)

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摘要： 本文基于2022年南海（17°N，116°E）站位直接观测的4000m湍流数据，对吕宋海峡的湍流混合参数（包括湍动能耗散率、混合率、Thorpe尺度等）的空间分布和相关性进行综合化研究，并验证MG（MacKinnon-Gregg）参数化模型在此断面的适用性。该断面真实的湍动能耗散率在O(10-9)Wkg-1左右，MG方法估算的耗散率在O(10-9~10-10)Wkg-1左右，平均混合率分别在O(10-4)m2s-1和O(10-5)m2s-1,量级较为接近，说明MG在此站位的估算精度较高。两种方法显示在深海【1300~4000m】范围内，混合率与Thorpe尺度的平均波动高度一致，整体呈现大-小-大-小的四层分布（“反z形”），相关系数均高达0.7，在【1300~3000m】深度段两种方法的结果较为一致，达到0.8。应用小波分析能量的多尺度级串，在高相关的位置能量变动更加明显，证明了引入混合率和Thorpe尺度相关系数分析湍流混合强度的重要性。本研究将直接观测与参数化估算结合，可对南海中深层的微结构观测、混合参数的空间分布以及湍流混合的理论研究提供有益参考。

关键词: 南海湍流混合, 微结构观测, Thorpe尺度, 湍耗散率, 混合率, MG模型

Abstract: Based on the turbulence data overall 4000 m directly observed at station of （17°N，116°E） in the South China Sea in 2022, this paper studies the spatial distribution and correlation of turbulent mixing parameters ( including dissipation rate, mixing rate, Thorpe scale, etc. ), and verifies the applicability of the MG (MacKinnon-Gregg) model in this station. The real turbulent kinetic energy dissipation rate is around O(10-9)Wkg-1, while the dissipation rate estimated with the MG method is around O(10-9~10-10)Wkg-1 ,whose average mixing rates were O(10-4)m2s-1 and O(10-5)m2s-1respectively, with a similar magnitude order, indicating that MG model at this station has a high estimation accuracy. The two methods show that in the range of 1300~4000m in the deep sea, mixing rate is highly consistent with the average fluctuation of Thorpe scale, showing the overall large-small-large-small distribution ("inverse-z shape"), and the correlation coefficient is as high as 0.7, especially results of which in the depth of [1300~3000m] are relatively consistent, both reaching 0.8. Applying wavelet to analyze the multiscale he two methods show that in the range of 1300~4000m in the deep sea, the mixing rate is highly consistent with the average fluctuation of Thorpe scale, showing the overall large-small-large-small distribution ("inverse-z shape"), and the correlation coefficient is as high as 0.7, especially results of which are relatively consistent in the depth of 1300~3000m, both reaching 0.8. Applying wavelet to analyze the multiscale series of the energy, the positional energy changes more significantly at high correlation, which demonstrate the importance of introducing the correlation coefficient of mixing rate and Thorpe scale to analyze the turbulent mixing intensity. This research combines direct observation with parameterization estimation, which can provide useful reference for microstructure observation, spatial distribution of mixing parameters and theoretical study of turbulent mixing in the intermediate and deep layers of the South China Sea.

Key words: Turbulence mixing in the South China sea, Thorpe scale, turbulent dissipation rate, mixing rate, MG model