南海东北部深层次的细结构观测与湍流混合研究*

doi:10.11978/2024201

Abstract

Abstract:

Based on direct turbulence measurements at 4000 m depth from Station H2 (17°N, 116°E) in the South China Sea in 2022, this study comprehensively investigates the vertical distribution and correlation of turbulent mixing parameters — including turbulent kinetic energy dissipation rate, mixing rate, Thorpe scale — in the northeastern South China Sea. The mixing rate and Thorpe scale characterize the turbulent mixing intensity from the perspectives of turbulent dissipation and water mass overturning, respectively. Both parameters exhibit consistent average fluctuations every 500 m in the 1500~4000 m depth range, diaplaying a four-layer “big-small-big-small” distribution (inverse z-shaped) with high correlation. The MacKinnon-Gregg parameterization model was applied to this station, yielding reliable estimates, with an overall correlation coefficient exceeding 0.7 between the estimated mixing rate and Thorpe scale. Based on their correlation coefficient distribution, we select depths with strong (1755 m) and weak (3785 m) correlations between the mixing rate and Thorpe scale for wavelet analysis. The results reveal more intense multi-scale energy cascade in regions of strong correlation, demonstrating that the correlation coefficient between parameters can effectively identify genuine turbulent mixing and filter out false errors caused by instrument noise or environmental factors. By combining fine-structure direct observations with parameterization methods, this study provides valuable insights into turbulence observation, the vertical distribution of mixing parameters and the evolution mechanisms of turbulent mixing in the middle and deep layers of the South China Sea.

Key words: turbulence mixing in the South China Sea, fine-scale observations, Thorpe scale, turbulent dissipation rate, mixing rate, MacKinnon-Gregg model

CLC Number:

P731.26

ZHU Xiaoyu, YANG Hua, MAO Beibei, ZHENG Yuxuan. Observations of fine-scale structure and study of turbulent mixing in the deep northeastern South China Sea^*[J].Journal of Tropical Oceanography, 2025, 44(5): 22-30.

Figures/Tables 9

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名称	性能参数
采样频率/Hz	1000
响应时间/ms	1
空间分辨率/mm	0.35
剪切流灵敏度/(V·m·s²·kg^-1)	2.68×10^-2
耗散率测量范围/(W·kg^-1)	1×10^-11~1×10^-4

Observations of fine-scale structure and study of turbulent mixing in the deep northeastern South China Sea^*

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Observations of fine-scale structure and study of turbulent mixing in the deep northeastern South China Sea*

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Observations of fine-scale structure and study of turbulent mixing in the deep northeastern South China Sea^*