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The influence of turbulent mixing on the subsurface chlorophyll maximum layer in the northern South China Sea

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Journal of Oceanology and Limnology 2021年第6期39卷 2167-2180页

作者： Chenjing SHANG Changrong LIANG Guiying CHEN Yongli GAO Shenzhen Key Laboratory of Marine Bioresources and Eco-environmental Science College of Life Science and OceanographyShenzhen UniversityShenzhen 518060China State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou) Guangzhou 511458China Equipment Public Service Center South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China

We present observations from deployments of turbulent microstructure instrument and CTD package in the northern South China Sea from April to May *** them we determined the turbulent mixing(dissipation rateεand diapycnal diffusivityκ),nutrients(phosphate,nitrate,and nitrite),nutrient fluxes,and chlorophyll a in two transects(A and B).Transect A was located in the region where turbulent mixing in the upper 100 m was weak(κ~10-6-10-4 m^(2)/s).Transect B was located in the region where the turbulent mixing in the upper 100 m was strong(κ~10-5-10-3 m^(2)/s)due to the influence of internal waves originating from the Luzon Strait and water intrusion from the Western *** both transects,there was a thin subsurface chlorophyll maximum layer(SCML)(>0.25 mg/m^(3))nested in the upper 100 *** observations indicate that the effects of turbulent mixing on the distributions of nutrients and chlorophyll a were different in the two *** the transect A with weak turbulent mixing,nutrient fluxes induced by turbulent mixing transported nutrients to the SCML but not to the upper *** were sufficient to support a local SCML phytoplankton population and the SCML remained *** the transect B with strong turbulent mixing,nutrient fluxes induced by turbulent mixing transported nutrients not only to the SCML but also to the upper water,which scatters the nutrients in the water column and diffuses the SCML.

关键词： turbulent mixing diapycnal diffusivity nutrients nutrient flux chlorophyll a

REVIEW OF turbulent mixing MODELS

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Acta Mathematica Scientia 2009年第6期29卷 1703-1720页

作者： Baolian Cheng Los Alamos National Laboratory Los Alamos NM 87545 USA

Fluid mixing is an important phenomenon in many physical applications from supernova explosions to genetic structure formations. In this paper, we overview some theoretical and empirical dynamic mix models, which have been developed over the recent decades, in particular, the ensemble-average micro physical mix model, the multifluid interpenetration mix model, the phenomenological and hybrid turbulent mix models, the buoyancy drag mix model, the single fluid turbulence mix model, and the large eddy simulation mix model. The similarities, distinctions, and connections between these models and their applications are discussed.

关键词： hydrodynamic instabilities turbulent mixing

Tides and turbulent mixing in the North of Taiwan Island

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Advances in Atmospheric Sciences 2019年第3期36卷 313-325,341页

作者： Xiangzhou SONG Dexing WU Xiaohui XIE State Oceanic Administration Ministry of Nat-ural Resources Physical Oceanography Laboratory Ocean University of China National Marine Environmental Forecasting Center State Oceanic Administration Horn Point Laboratory University of Maryland Center for Environmental Science

Microstructure and hydrological profiles were collected along two cross-shelf sections from the deep slope to the shallow water in the north of Taiwan Island in the summer of *** the tidal currents on the shelf were dominated by the barotropic tide with the current ellipse stretched across the shelf,significant internal tides were observed on the *** depth-mean turbulent kinetic energy(TKE)dissipation rate on the shelf was 10^-6W kg^-1,corresponding to a diapycnal diffusivity of 10^-2 m^2s^-*** depth-mean TKE dissipation rate on the slope was 1×10^-7 Wkg^-1,with diapycnal diffusivity of 3×10^-4m^2s^-*** shear instability associated with internal tides largely contributed to the TKE dissipation rate on the slope from the surface to 150 m,while the enhanced turbulence on the shelf was dominated by tidal or residual current dissipations caused by friction in the thick bottom boundary layer(BBL).In the BBL,the Ekman currents associated with the northeastward Taiwan Warm Current were identified,showing a near-bottom velocity spiral,which agreed well with the analytical bottom Ekman solution.

关键词： microstructure observations turbulent mixing internal tides bottom boundary layer bottom Ekman spiral

Observed characteristics of flow,water mass,and turbulent mixing in the Preparis Channel

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Acta Oceanologica Sinica 2023年第2期42卷 83-93页

作者： Ruijie Ye Feng Zhou Xiao Ma Dingyong Zeng Feilong Lin Hongliang Li Chenggang Liu Soe Moe Lwin Hlaing Swe Win Soe Pyae Aung State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou310012China School of Oceanography Shanghai Jiao Tong UniversityShanghai200030China Geology Department Dagon UniversityYangon11422Myanmar National Analytical Laboratory Department of Research Innovation Ministry of EducationYangon11061Myanmar Port and Harbour Engineering Department Myanmar Maritime UniversityYangon11293Myanmar

Preparis Channel is the very important exchange path of energy and materials between the northern Bay of Bengal and Andaman Sea(AS).A set of hydrographic measurements,a microstructure profiler,and a deep mooring were used to determine the characteristics of water masses,turbulent mixing,and flows in the Preparis *** unprecedented short-term mooring data reveal that a deep current in the deep narrow passage(below 400 m)of the Preparis Channel flows toward the Bay of Bengal(BoB)with a mean along-stream velocity of 25.26 cm/s at depth of 540 m;above the deep current,there are a relatively weak current flows toward the AS with a mean along-stream velocity of 15.46 cm/s between 500 m and 520 m,and another weak current flows toward the BoB between 430 m and 500 ***,a sandwiched vertical structure of deep currents(below 400 m)is present in the Preparis *** volume transport below 400 m is 0.06 Sv(1 Sv=106 m^(3)/s)from the AS to the *** the upper layer(shallower than 300 m),the sea water of the AS is relatively warmer and fresher than that in the BoB,indicating a strong exchange through the *** profiler observations reveal that the turbulent diffusivity in the upper layer of the Preparis Channel reaches O(10−4 m^(2)/s),one order larger than that in the interior of the BoB and over the continental slope of the northern *** speculate that energetic high-mode internal tides in the Preparis Channel contribute to elevated turbulent *** addition,a local“hotspot”of turbidity is identified at the deep mooring site,at depth of about 100 m,which corresponds to the location of elevated turbulent mixing in the Preparis Channel.

关键词： deep flow turbulent mixing water mass Preparis Channel

Observations of upper layer turbulent mixing in the southern South China Sea

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Acta Oceanologica Sinica 2015年第11期34卷 6-13页

作者： SHANG Xiaodong QI Yongfeng CHEN Guiying LIANG Changrong State Key Laboratory of Tropical Oceanography South China Sea Institute of Oceanology Chinese Academy of Sciences University of Chinese Academy of Sciences

A turbulent microstructure experiment was undertaken at a low latitude of 10°N in the South China Sea in late August 2012. The characteristics of the eddy diffusivity above 650 m were analyzed, which is one order of magnitude larger than that in the open ocean at that low latitude. Enhanced eddy diffusivities by strong shears and sharp changes in topography were observed. The strongest eddy diffusivity occurred in the mixed layer, and it reached O（10^-2 m^2/s）. Strong stratification in the thermocline inhibited the penetration of surface eddy diffusivities through the thermocline, where the mixing was weakest. Below the thermocline, where the background eddy diffusivity was approximately O（10^-6 m^2/s）, the eddy diffusivity increased with depth, and its largest value was O（10^-3 m^2/s）.

关键词： southern South China Sea turbulent mixing dissipation rate topography

Spatial structure of turbulent mixing of an anticyclonic mesoscale eddy in the northern South China Sea

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Acta Oceanologica Sinica 2020年第11期39卷 69-81页

作者： Yongfeng Qi Chenjing Shang Huabin Mao Chunhua Qiu Changrong Liang Linghui Yu Jiancheng Yu Xiaodong Shang State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Shenzhen Key Laboratory of Marine Bioresources and Eco-environmental Science College of Life Science and OceanographyShenzhen UniversityShenzhen 518060China Ocean College Zhejiang UniversityZhoushan 316021China The Center for Coastal Ocean Science and Technology School of Marine SciencesSun Yat-sen UniversityGuangzhou 510275China State Key Laboratory of Robotics Shenyang Institute of AutomationChinese Academy of SciencesShenyang 110016China

Upper turbulent mixing in the interior and surrounding areas of an anticyclonic eddy in the northern South China Sea(SCS)was estimated from underwater glider data(May 2015)in the present study,using the Gregg-HenyeyPolzin parameterization and the Thorpe-scale *** observations revealed a clear asymmetrical spatial pattern of turbulent mixing in the anticyclonic eddy *** diffusivity(in the order of 10–3 m2/s)was found at the posterior edge of the anticyclonic mesoscale eddy;on the anterior side,diffusivity was one order of magnitude lower on *** asymmetrical pattern was highly correlated with the eddy kinetic *** shear variance on the posterior side,which is conducive to the triggering of shear instability,may be the main mechanism for the elevated *** addition,the generation and growth of sub-mesoscale motions that are fed by mesoscale eddies on their posterior side may also promote the occurrence of strong mixing in the studied *** results of this study help improve our knowledge regarding turbulent mixing in the northern SCS.

关键词： mesoscale eddy turbulent mixing South China Sea GHP parameterization Thorpe-scale method

Macro and micro issues in turbulent mixing

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Science China(Technological Sciences) 2013年第10期56卷 2355-2360页

作者： MELVIN J KAUFMAN R LIM H KAMAN T RAO P GLIMM J Department of Applied Mathematics and Statistics Stony Brook UniversityStony Brook NY 11794 USA

Numerical prediction of turbulent mixing can be divided into two subproblems: to predict the geometrical extent of a mixing region and to predict the mixing properties on an atomic or molecular scale, within the mixing region. The former goal suffices for some purposes, while important problems of chemical reactions(e.g. flames) and nuclear reactions depend critically on the second goal in addition to the first one. Here we review recent progress in establishing a conceptual reformulation of convergence, and we illustrate these concepts with a review of recent numerical studies addressing turbulence and mixing in the high Reynolds number limit. We review significant progress on the first goal, regarding the mixing region, and initial progress on the second goal, regarding atomic level mixing properties. New results concerning non-uniqueness of the infinite Reynolds number solutions and other consequences of a renormalization group point of view, to be published in detail elsewhere, are summarized *** notion of stochastic convergence(of probability measures and probability distribution functions) replaces traditional pointwise convergence. The primary benefit of this idea is its increased stability relative to the statistical "noise" which characterizes turbulent flow. Our results also show that this modification of convergence, with sufficient mesh refinement, may not be needed. However, in practice, mesh refinement is seldom sufficient and the stochastic convergence concepts have a *** to this circle of ideas is the observation that turbulent mixing, in the limit of high Reynolds number, appears to be non-unique. Not only have multiple solutions been observed(and published) for identical problems, but simple physics based arguments and more refined arguments based on the renormalization group come to the same *** of the non-uniqueness inherent in numerical models of high Reynolds number turbulence and mixing, we also include here numeri

关键词： stochastic convergence turbulent mixing renormalization group dynamic subgrid scale models

Beam quality in a turbulent mixing medium

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Chinese Journal of Lasers 1992年第3期 23-29页

作者： Chuanbao Wu, Baogen Wu, Shirun Yang, Yue Zhang (Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080. PRC)

A criterion for evaluating beam quality is *** dividing the mediumdisturbances into the ordered and random part, introducing the time-averaged variance ofphase distortion and fitting the wavefront with Zernike polynom... 详细信息

关键词： gas flow laser turbulent mixing beam quality

turbulent dissipation and mixing in Prydz Bay

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Chinese Journal of Oceanology and Limnology 2013年第2期31卷 445-453页

作者：杨庆轩田纪伟赵玮谢玲玲 Physical Oceanography Laboratory Ocean University of China outh China Sea Environmental Institute Guangdong Ocean University

In this paper, we present measurements of velocity, temperature, salinity, and turbulence collected in Prydz Bay, Antarctica, during February, 2005. The dissipation rates of turbulent kinetic energy （e） and diapycnal diffusivities （Ks） were estimated along a section in front of the Amery Ice Shelf. The dissipation rates and diapycnal diffusivities were spatially non-uniform, with higher values found in the western half of the section where E reached 10.7 W/kg and Kz reached 10.2 mVs, about two and three orders of magnitude higher than those in the open ocean, respectively. In the western half of the section both the dissipation rates and diffusivities showed a high-low-high vertical structure. This vertical structure may have been determined by internal waves in the upper layer, where the ice shelf draft acts as a possible energy source, and by bottom-generated internal waves in the lower layer, where both tides and geostrophic currents are possible energy sources. The intense diapycnal mixing revealed in our observations could contribute to the production of Antarctic Bottom Water in Prydz Bay.

关键词： turbulent mixing Prydz Bay Antarctic Bottom Water (AABW) microstructure observation