搜索到54篇“ HALOCLINE“的相关文章
Oceanic vertical mixing of the lower halocline water in the Chukchi Borderland and Mendeleyev Ridge
2021年
Oceanic vertical mixing of the lower halocline water(LHW)in the Chukchi Borderland and Mendeleyev Ridge was studied based on in situ hydrographic and turbulent observations.The depth-averaged turbulent dissipation rate of LHW demonstrates a clear topographic dependence,with a mean value of 1.2×10^(-9) W/kg in the southwest of Canada Basin,1.5×10^(-9) W/kg in the Mendeleyev Abyssal Plain,2.4×10^(-9) W/kg on the Mendeleyev Ridge,and2.7×10^(-9) W/kg on the Chukchi Cap.Correspondingly,the mean depth-averaged vertical heat flux of the LHW is0.21 W/m^(2) in the southwest Canada Basin,0.30 W/m^(2) in the Mendeleyev Abyssal Plain,0.39 W/m^(2) on the Mendeleyev Ridge,and 0.46 W/m^(2) on the Chukchi Cap.However,in the presence of Pacific Winter Water,the upward heat released from Atlantic Water through the lower halocline can hardly contribute to the surface ocean.Further,the underlying mechanisms of diapycnal mixing in LHW—double diffusion and shear instability—was investigated.The mixing in LHW where double diffusion were observed is always relatively weaker,with corresponding dissipation rate ranging from 1.01×10^(-9) W/kg to 1.57×10^(-9) W/kg.The results also show a strong correlation between the depth-average dissipation rate and strain variance in the LHW,which indicates a close physical linkage between the turbulent mixing and internal wave activities.In addition,both surface wind forcing and semidiurnal tides significantly contribute to the turbulent mixing in the LHW.
Long LinHailun HeYong CaoTao LiYilin LiuMingfeng Wang
Characteristics of the Internal Waves Generated by a Towed Model with Rotating Propeller Under a Strong Halocline被引量:3
2019年
Experiments are performed on the internal waves(IWs) generated by a towed model with rotating propeller in a density-stratified fluid with linear halocline; the Reynolds number ranges from 7 000 to 84 000, and the Froude number ranges from 0.7 to 8.1. The wave speed, amplitude and patterns are investigated on the basis of the multi-channel conductivity probe array technology and the cross correlation analysis method. It is shown that the propeller advances the transition from the body-generated IWs to the wake-generated IWs. Before the transition, the IWs are stationary to the translational model. An extra V-shaped wave with a narrow opening angle is generated by the propeller and the wave amplitude becomes larger with the increase of the thrust momentum,indicating that the propeller produces body and wake effects at the same time before the transition. After the transition, the Froude number associated with the wave speed drops down and fluctuates within 0.4—1.5, showing that the IWs are nonstationary to the model. The interaction of the drag momentum and the thrust momentum changes the characteristics of the wave amplitudes and patterns. The wave amplitude no longer simply grows with the Froude number but depends on the contrast of the drag momentum and the thrust momentum. Experimental results show that the most obvious contrast of the wave pattern contour maps appears when the drag momentum and the thrust momentum have the largest difference if other conditions are the same. When the ratio of the drag momentum to the thrust momentum is within 1—10, the wake can be considered as zero-momentum, meaning that the momentum difference is not enough to generate large scale structures in the wake.
DUAN NingyuanCHEN KeWANG HongweiYOU Yunxiang
Regime shift of the dominant factor for halocline depth in the Canada Basin during 1990–2008被引量:1
2017年
The World Ocean Database(WOD) is used to evaluate the halocline depth simulated by an ice-ocean coupled model in the Canada Basin during 1990–2008. Statistical results show that the simulated halocline is reliable.Comparing of the September sea ice extent between simulation and SSM/I dataset, a consistent interannual variability is found between them. Moreover, both the simulated and observed September sea ice extent show staircase declines in 2000–2008 compared to 1990–1999. That supports that the abrupt variations of the ocean surface stress curl anomaly in 2000–2008 are caused by rapid sea ice melting and also in favor of the realistic existence of the simulated variations. Responses to these changes can be found in the upper ocean circulation and the intermediate current variations in these two phases as well. The analysis shows that seasonal variations of the halocline are regulated by the seasonal variations of the Ekman pumping. On interannual time scale, the variations of the halocline have an inverse relationship with the ocean surface stress curl anomaly after 2000,while this relationship no longer applies in the 1990 s. It is pointed out that the regime shift in the Canada Basin can be derived to illustrate this phenomenon. Specifically, the halocline variations are dominated by advection in the 1990 s and Ekman pumping in the 2000 s respectively. Furthermore, the regime shift is caused by changing Transpolar Drift pathway and Ekman pumping area due to spatial deformation of the center Beaufort high(BH)relative to climatology.
MU LongjiangZHAO JinpingZHONG Wenli
Weak Vertical Diffusion Allows Maintenance of Cold Halocline in the Central Arctic被引量:6
2009年
In spring preceding the record minimum summer ice cover detailed microstructure measurements were made from drifting pack ice in the Arctic Ocean, 110 km from the North Pole. Profiles of hydrography, shear, and temperature microstructure collected in the upper water column covering the core of the Atlantic Water are analyzed to determine the diapycnal eddy diffusivity, the eddy diffusivity for heat, and the turbulent flux of heat. Turbulence in the bulk of the cold halocline layer was not strong enough to generate significant buoyancy flux and mixing. Resulting turbulent heat flux across the upper cold halocline was not significantly different than zero. The results show that the low levels of eddy diffusivity in the upper cold halocline lead to small vertical turbulent transport of heat, thereby allowing the maintenance of the cold halocline in the central Arctic.
Ilker FER
南海东北部陆架坡折海域跃层判定探讨被引量:7
2006年
以南海东北部陆架坡折海域为例,探讨了浅海(水深<200m)和开阔海区(水深>200m)跃层在陆架坡折海域的水平衔接问题。对多组实测CTD断面水温、盐度和声速跃层的诊断分析结果表明,冬季和春季基本可不考虑陆架坡折海域跃层的水平衔接问题;夏季和秋季陆架坡折海域温、盐、声速跃层判据可分别取0.1℃.m-1、0.02m-1和0.30s-1,来保证跃层的水平连续分布。此外,在可能的内潮存在情况下,为保证跃层水平分布的连续性,可统一取开阔海区的跃层判据。
潘爱军郭小钢许金电万小芳吴日升
关键词:南海东北部温跃层
A double-halocline structure in the Canada Basin of the Arctic Ocean被引量:5
2005年
A year-round halocline is a particular hydrographic structure in the upperArctic Ocean. On the basis of an analysis of the hydrographic data collected in the Arctic Ocean, itis found that a double-halocline structure exists in the upper layer of the southern Canada Basin,which is absolutely different from the Cold Halocline Layer (CHL) in the Eurasian Basin. ThePacific-origin water is the primary factor in the formation of the double-halocline structure. Theupper halocline lies between the summer modification and the winter modification of thePacific-origin water while the lower halocline results from the Pacific-origin water overlying uponthe Atlantic-origin water. Both haloclines are all the year-round although seasonal and interannualvariations have been detected in the historical data.
SHI Jiuxin ZHAO Jinping LI Shujiang CAO Yong QU Ping
The sources of the upper and lower halocline water in the Canada Basin derived from isotopic tracers被引量:10
2003年
Seawater samples were collected in the water column from the Canada Basin aboard RV Xuelong in August 1999. Concentrations of δ; D, δ;18 O, nutrients (NO3 -, PO4 3-, SiO3 2-) and dissolved oxygen were measured, along with hydrographic parameters (salinity and temperature). Our results showed that the upper layer of the water column was characterized by the occurrence of the upper halocline water (UHW) and the lower halocline water (LHW). The UHW was associated with a salinity of 33.1 (~150m depth) and maximums of nutrients, NO and PO*, whereas minimums of NO and PO* (PO* = PO4 3?+ O2/175?1.95 μmol/dm3) occurred at the depth of LHW (~300m depth). Two tracer systems, S-δ;18O-PO* and S-δ D-SiO3 3-, were used to estimate the fractions of the Atlantic water, Pacific water, river runoff and sea ice meltwater in water samples. Combined with the nutrient ratio NO/PO, it was suggested that the UHW was derived from the in-flow of the Pacific water through the Bering Strait. These waters were modified to obtain the high salinity and nutrients in the Chukchi shelf or/and the east Siberian shelf. The LHW was maintained by inflow of the Atlantic water through Barents Sea and subsequent mixing with freshwater in the shelf region to produce the signals of NO and PO* minimums. In study basin, the river runoff signals were confined to water depths less than 300 m and the fractions of river runoff decreased with the increasing depth. Water column inventories of river runoff and sea ice meltwater were calculated between the surface and 300m. The river runoff inventories in the Canada Basin were higher than those in other sea areas, suggesting that the Canada basin is a major storage region for Arctic river water. The sea ice meltwater signals suggested that the Canada Basin is a region of net sea ice formation and the inventories of net sea ice in the upper water column increasing from the south to the north.
陈敏黄奕普金明明邱雨生
关键词:HALOCLINEWATERCANADA
北冰洋盐跃层研究进展被引量:14
2003年
长年存在的盐跃层是北冰洋上层海洋独有的结构之一 ,对维持北冰洋表层的低温特征和海冰存在起着非常重要的作用。在过去的十几年中 ,北冰洋气候系统发生了前所未有的异常变化 ,北冰洋盐跃层也经历了从消退到近乎恢复的戏剧性变化。因此 ,北冰洋及其盐跃层的研究得到了广泛的重视。介绍了有关北冰洋盐跃层研究的进展情况 ,并对研究中存在的问题以及未来的发展进行了分析和阐述。有关北冰洋盐跃层的形成问题 ,先后有平流机制、对流机制等多种观点。认为由于现在欧亚海盆表层盐度普遍增高 ,其盐跃层的形成当以对流机制为主 ;而平流机制则更加适用于加拿大海盆的盐跃层。 2 0世纪 90年代 ,在北冰洋观测到一系列异常变化 ,包括盐跃层退缩、大西洋层增暖和北极海冰减少。实际上 ,这些变化是紧密联系在一起的 。
史久新赵进平
关键词:盐跃层年际变化
关于跃层深度确定方法的探讨被引量:25
2001年
本文针对不同类型的资料,对确定温跃层、盐跃层和密度跃层深度的几种方法进行了较为细致地比较和讨论。文章表明,采用不同的资料分析方法所得的跃层深度存在差异。在采用高精度资料进行跃层分析时应滤掉小尺度变化所带来的影响。分析方法的选取应根据研究目的和拥有资料情况来决定。在采用垂向梯度法进行跃层分析时,要注意深浅水交界处跃层分析的连续性问题。
吴巍方欣华吴德星
关键词:温跃层盐跃层密度跃层
黄、东海温盐跃层的分布特征及其季节变化被引量:62
2001年
利用“中韩水循环动力学合作研究”和“中国近海海洋环境综合调查”( 1 996年 4月 -1 999年 1月 )期间各季节 1 2 8°E以西的校正后的 CTD现场水文调查资料 ,对黄、东海温、盐跃层在 4个不同时期 (成长、强盛、消衰和无跃期 )的各特征值的分布特性及其季节变化作了探讨和分析。结果表明 :( 1 )黄海底层显著冷水团的存在 ,使黄海以温跃层占绝对主导地位 ;东海的沿岸海区因受长江径流的影响则以盐跃层为主导。 ( 2 )温跃层的强度主要取决于与其相联的上、下层水团的强弱。冷水团的存在是产生强跃层的根本原因。( 3)夏季东海区双温跃层从浙江近海到济州岛以南水域连成片 ,其分布范围恰好与冬季入侵陆架的黑潮水相一致。 ( 4 )长江冲淡水舌状盐跃层强度等值线在各季节的伸展情况反映了长江冲淡水在各季节的扩散情况 ,一年当中 ,其轴向先从南往北转 ,再从北往南转。 ( 5 )
邹娥梅熊学军郭炳火林葵
关键词:盐跃层特征值温跃层