夏季长江河口层化与湍流混合特征分析

doi:10.11978/2017129

热带海洋学报 ›› 2018, Vol. 37 ›› Issue (5): 33-39.doi: 10.11978/2017129CSTR: 32234.14.2017129

夏季长江河口层化与湍流混合特征分析

林姚坤^1,²(), 包芸¹, 陈起程², 吴加学²()

1. 中山大学力学系, 广东广州510275
2. 中山大学海洋科学学院, 广东广州510275

收稿日期:2017-12-12 修回日期:2018-01-26 出版日期:2018-09-20 发布日期:2018-10-13
作者简介:
作者简介: 林姚坤(1992—), 男, 硕士研究生, 主要从事河口动力学研究。E-mail: linyk8@mail2.sysu.edu.cn
基金资助:
国家重大科学研究计划全球气候变化研究专题(2013CB956502);国家自然科学基金面上项目(41576091)

Summertime stratification and turbulent mixing in the Yangtze Estuary

Yaokun LIN^1,²(), Yun BAO¹, Qicheng CHEN², Jiaxue WU²()

1. Department of Mechanics, Sun Yat-sen University, Guangzhou 510275, China
2. School of Marine Sciences, Sun Yat-sen University, Guangzhou 510275, China

Received:2017-12-12 Revised:2018-01-26 Online:2018-09-20 Published:2018-10-13
Supported by:
National Basic Research Program of China (2013CB956502);National Natural Science Foundation of China (41576091)

摘要/Abstract

摘要：

利用2016年夏季长江河口现场水文特性与湍流微结构观测资料, 分析了长江河口水体温盐结构、层化发育、湍流与混合特征。结果表明: 1)夏季长江河口水体密度层化结构明显, 根据各层水体密度梯度差异, 可将水体分为底部混合层和上层密度跃层, 两部分的密度层化界限与浮力频率等值线lg N ²= - 4.0接近。2)底部混合层湍动能耗散率大, 层化结构弱, 水体分层稳定性弱; 上层密度跃层湍动能耗散小, 层化结构强, 水体分层稳定性强, 这有利于河口内波的发育与传播。3)在密度层化的作用下, 水体的湍动能耗散率、湍动能剪切生成及浮力通量的能量关系在一定范围内符合湍动能局部能量平衡方程。不同层之间的湍流弗劳德数Fr_t和湍流雷诺数Re_t在Fr_t-Re_t平面上呈现明显的分区, 与经典的分层剪切流理论基本吻合。

关键词: 分层流, 浮力频率, 底部混合层, 上层密度跃层, 长江河口

Abstract:

Hydrological and turbulent microstructural observations were conducted in summer 2016 to analyze the summertime stratification and turbulent mixing in the Yangtze Estuary. The temporal and spatial distributions of salinity, temperature, stratification, and turbulent mixing showed highly-stratified structures in the estuary. The vertical distributions of density vertical gradient in different layers demonstrated bottom mixed layer and upper pycnocline, where a division of the stratification was approximately along the contour line of lgN ² = - 4.0. The bottom mixed layer had a stronger dissipation rate and unstably-stratified structure, while the upper pycnocline had a weaker dissipation rate and stably-stratified structure, where the formation and spread of internal waves would occur. Under the condition of stratified structure, the dissipation rate, turbulent shear production and buoyancy flux were found to satisfy the local turbulent kinetic energy balance. Turbulent Reynolds number Re_t and turbulent Froude number Fr_tin the bottom mixed layer and the upper pycnocline were distributed in different regions of the Re_t-Fr_t space, indicating that the stratification and mixing in the estuary was in line with the classical theory of Ivey and Imberger (1991).

Key words: stratified flow, buoyancy frequency, bottom mixed layer, upper pycnocline, Yangtze Estuary

中图分类号:

P731.26

林姚坤, 包芸, 陈起程, 吴加学. 夏季长江河口层化与湍流混合特征分析[J]. 热带海洋学报, 2018, 37(5): 33-39.

Yaokun LIN, Yun BAO, Qicheng CHEN, Jiaxue WU. Summertime stratification and turbulent mixing in the Yangtze Estuary[J]. Journal of Tropical Oceanography, 2018, 37(5): 33-39.

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参考文献 17

[1]	吕华庆, 2012. 物理海洋学基础[M]. 北京: 海洋出版社: 27-29.
	LV HUAQING, 2012. Physical oceanographic basis[M]. Beijing: Ocean Press: 27-29 (in Chinese).
[2]	任杰, 刘宏坤, 贾良文, 等, 2012. 磨刀门水道盐度混合层化机制[J]. 水科学进展, 23(5): 715-720.
	REN JIE, LIU HONGKUN, JIA LIANGWEN, et al, 2012. Research on salinity mixing and stratification mechanisms at the Modaomen channel[J]. Advances in Water Science, 23(5): 715-720 (in Chinese with English abstract).
[3]	王子龙, 王延辉, 刘玉红, 等, 2012. 海洋微结构湍流垂直剖面仪模态分析方法[J]. 机械设计, 29(4): 89-92.
	WANG ZILONG, WANG YANHUI, LIU YUHONG, et al, 2012. Modal analysis method of ocean microstructure turbulence vertical profiler[J]. Journal of Machine Design, 29(4): 89-92 (in Chinese with English abstract).
[4]	叶安乐, 李凤岐, 1992. 物理海洋学[M]. 青岛: 海洋大学出版社: 684.
	YE ANLE, LI FENGQI, 1992. Physical oceanography [M]. Qingdao: Ocean University Press: 684 (in Chinese).
[5]	FISCHER H B, LIST E J, KOH R C Y, et al, 1979. Mixing in inland and coastal waters[M]. New York: Academic Press, Inc: 593-594.
[6]	GEYER W R, 1993. The importance of suppression of turbulence by stratification on the estuarine turbidity maximum[J]. Estuaries, 16(1): 113-125.
[7]	HANSEN D V, RATTRAY M, 1966. Gravitational circulation in straits and estuaries[J]. Journal of Marine Research, 23: 104-122.
[8]	HOLT S E, KOSEFF J R, FERZIGER J H, 1992. The evolution of turbulence in the presence of mean shear and stable stratification[J]. Journal of Fluid Mechanics, 237: 499-539.
[9]	IVEY G N, IMBERGER J, KOSEFF J R, 1998. Buoyancy fluxes in a stratified fluid[M]//IMBERGER J. Physical Processes in Lakes and Oceans. Washington, DC: American Geophysical Union Press: 377-388.
[10]	IVEY G N, IMBERGER J, 1991. On the nature of turbulence in a stratified fluid. Part I: The energetics of mixing[J]. Journal of Physical Oceanography, 21(5): 650-658.
[11]	KOLMOGOROV A, 1941. The local structure of turbulence in incompressible viscous fluid for very large Reynolds' numbers[J]. Doklady Akademiia Nauk SSSR, 30(4): 301-305.
[12]	MOUM J N, RIPPETH T P, 2009. Do observations adequately resolve the natural variability of oceanic turbulence?[J]. Journal of Marine Systems, 77(4): 409-417.
[13]	OAKEY N S, ELLIOTT J A, 1982. Dissipation within the surface mixed layer[J]. Journal of Physical Oceanography, 12(2): 171-185.
[14]	PRITCHARD D W, KENT R E, 1956. A method for determining mean longitudinal velocities in a coastal plain estuary[J]. Journal of Marine Research, 15(1): 81-91.
[15]	SIMPSON J H, BROWN J, MATTHEWS J, et al, 1990. Tidal straining, density currents, and stirring in the control of estuarine stratification[J]. Estuaries, 13(2): 125-132.
[16]	SIMPSON J H, WILLIAMS E, BRASSEUR L H, et al, 2005. The impact of tidal straining on the cycle of turbulence in a partially stratified estuary[J]. Continental Shelf Research, 25(1): 51-64.
[17]	WINTERWERP J C, 2001. Stratification effects by cohesive and noncohesive sediment[J]. Journal of Geophysical Research: Oceans, 106(C10): 22559-22574.

站位	测量方式	仪器	采样频率/Hz	距底高度	测量要素
走航剖面	剖面观测	MSS-90L 微结构剖面仪	1024	—	温度、电导率、浊度、流速剪切
定点站位	剖面观测	MSS-90L 微结构剖面仪	1024	—	温度、电导率、浊度、流速剪切
	座底观测	RDI-ADCP 流速剖面仪	1	1.6m	剖面速度
	座底观测	ADV(两层) 三维点式流速仪	32	0.25m、 0.7m	底层流速

夏季长江河口层化与湍流混合特征分析

Summertime stratification and turbulent mixing in the Yangtze Estuary

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