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1.
In this study, we develop a variable-grid global ocean general circulation model(OGCM) with a fine grid(1/6)°covering the area from 20°S–50°N and from 99°–150°E, and use the model to investigate the isopycnal surface circulation in the South China Sea(SCS). The simulated results show four layer structures in vertical: the surface and subsurface circulation of the SCS are characterized by the monsoon driven circulation, with basin-scaled cyclonic gyre in winter and anti-cyclonic gyre in summer. The intermediate layer circulation is opposite to the upper layer, showing anti-cyclonic gyre in winter but cyclonic gyre in summer. The circulation in the deep layer is much weaker in spring and summer, with the maximum velocity speed below 0.6 cm/s. In fall and winter, the SCS deep layer circulation shows strong east boundary current along the west coast of Philippine with the velocity speed at 1.5 m/s, which flows southward in fall and northward in winter. The results have also revealed a fourlayer vertical structure of water exchange through the Luzon Strait. The dynamics of the intermediate and deep circulation are attributed to the monsoon driving and the Luzon Strait transport forcing. 相似文献
2.
A P - vector method is optimized using the variational data assimilation technique(VDAT). The absolute geostrophic velocity fields in the vicinity of the Luzon Strait (LS) are calculated, the spatial structures and seasonal variations of the absolute geostrophic velocity field are investigated. Our results show that the Kuroshio enters the South China Sea (SCS) in the south and middle of the Luzon Strait and flows out in the north, so the Kuroshio makes a slight clockwise curve in the Luzon Strait, and the curve is strong in winter and weak in summer. During the winter, a westward current appears in the surface, and locates at the west of the Luzon Strait. It is the north part of a cyclonic gyre which exits in the northeast of the SCS; an anti-cyclonic gyre occurs on the intermediate level, and it exits in the northeast of the SCS, and an eastward current exits in the southeast of the anti-cyclonic gyre. 相似文献
3.
通过一个全球的二维诊断模型,采用Levitus温盐资料和COADS风应力资料,并结合动力计算来研究南海上层环流的季节变化。计算结果与其它模式结果和观测结果非常相似。南海北部(南部)全年存在一气旋式(反气旋式)环流。在冬季气旋式环流几乎占据了整个南海,夏季则以反气旋式环流为主。泰国湾的环流在冬季(夏季)是气旋式的(反气旋的)。南海的西边界流有明显的季节变化,其在冬季从卡里马塔海峡流出南海,夏季部分西边界流从台湾海峡流出南海。越南离岸流在春季就开始出现,其位置比夏季的越南离岸流的位置偏北。 相似文献
4.
A numerical study of the summertime flow around the Luzon Strait 总被引：3，自引：0，他引：3
Luzon Strait, a wide channel between Taiwan and Luzon islands, connects the northern South China Sea and the Philippine Sea.
The Kuroshio, South China Sea gyre, monsoon and local topography influence circulation in the Luzon Strait area. In addition,
the fact that the South China Sea is a fairly isolated basin accounts for why its water property differs markedly from the
Kuroshio water east of Luzon. This work applies a numerical model to examine the influence of the difference in the vertical
stratification between the South China Sea and Kuroshio waters on the loop current of Kuroshio in the Luzon Strait during
summer. According to model results, the loop current’s strength in the strait reduces as the strongly stratified South China
Sea water is driven northward by the southwest winds. Numerical results also indicate that Kuroshio is separated by a nearly
meridional ridge east of Luzon Strait. The two velocity core structures of Kuroshio can also be observed in eastern Taiwan.
Moreover, the water flowing from the South China Sea contributes primarily to the near shore core of Kuroshio. 相似文献
5.
南海环流动力机制研究综述 总被引：40，自引：9，他引：31
南海的环流复杂,但通过近20 a来的研究工作,国内外学者对此已取得了不少的成果.本文就南海环流框架性的问题,综述了有关的文献,认为对南海上层海洋三方面的环流分量的驱动机制已有了初步的认识.这三方面分别是:(1)准季节性风场;(2)黑潮向南海的净输运;(3)黑潮向南海的涡度平流输送.但是对这些驱动的时空变化仍相当不清楚.三者皆增强了南海北部的海盆尺度气旋式环流,其强化的西南向西边界流靠近东沙群岛,建议称为“东沙海流”.没有水文证据显示黑潮水是以分支形式进入南海,其向南海的输运也不可能主要通过中尺度涡过程,具体机制有待研究.每年在南海生成的中尺度涡平均约有10个,风场与沿岸地形所生成的强风应力旋度可能是其主要的驱动机制.作为框架性的认识,也有三方面的工作进行得较少,即:(1)吕宋海峡的上层水交换;(2)南海的中尺度涡生成机制,虽然强风应力旋度及前述的第三种环流驱动机制也有中尺度涡伴生;(3)自吕宋海峡进入的深层水对南海上层海洋环流的影响. 相似文献
6.
A high-resolution, regional, numerical-model-based, real-time ocean prediction system for the northern South China Sea, called the Northern South China Sea Nowcast/Forecast System (NSCSNFS), has been used to investigate subtidal mesoscale flows during the time period of the Asian Seas International Acoustic Experiment (ASIAEX) field programs. The dynamics are dominated by three influences; 1) surface wind stress, 2) intrusions of the Kuroshio through Luzon Strait, and 3) the large-scale cyclonic gyre that occupies much of the northern South China Sea. Each component primarily drives currents in the upper ocean, so deep currents are rather weak. Wind stress is especially effective at forcing currents over the shallow China shelf. The Kuroshio intrusion tends to flow westward until it meets the northern edge of the large-scale cyclonic gyre. Together, these currents produce an intense, narrow jet directed northwest toward the continental slope, often in the region of the ASIAEX field programs. Upon reaching the slope, the current splits with part flowing northeastward along the slope and part flowing southwestward, producing large horizontal and vertical shears and making this region dynamically very complicated and difficult to simulate. The Kuroshio intrusion tends to be stronger (weaker) when the northeasterly winds are strong (weak) and the large-scale gyre is farther south (north), consistent with conclusions from previous model studies. At the northern boundary, the model produces a persistent northward flow through Taiwan Strait into the East China Sea. Data assimilation in the NSCSNFS model is shown to dampen the system, extracting energy and causing the entire system to spin down. 相似文献
7.
南海是西北太平洋最大的边缘海, 是联系北太平洋和北印度洋的关键通道。黑潮北上经过吕宋海峡时会将来自西太平洋的信号传入南海, 进而影响南海的水动力环境。研究了南海次表层盐度的空间分布特征、低频变化规律及其与太平洋年代际振荡(Pacific Decadal Oscillation, PDO)的关系, 并进一步探究了次表层盐度近年来的变化。结果显示: 1)南海次表层高盐水的位势密度主要介于24~26σθ, 受次表层气旋式环流所驱动, 盐度气候态空间分布北高南低, 以吕宋海峡处为起点, 呈逆时针自北向南逐渐降低。2)次表层盐度低频变化显著, 与PDO呈显著的正相关关系。当PDO处于正位相时, 吕宋海峡处西向平流输送加强, 次表层盐度升高; 当PDO处于负位相时, 吕宋海峡处西向平流输送减弱, 次表层盐度降低, 盐度的变化受到水平环流场的直接影响。3)近年来, 南海次表层盐度呈现先降低后升高再降低的趋势, 滞后PDO约10个月, 2006— 2014年初, 盐度呈下降趋势; 2014—2017年初, 盐度呈上升趋势, 且上升速率远大于先前下降的速率; 2017年后盐度再次逐渐降低。 相似文献
8.
Primary Study of the Mechanism of Eddy Shedding from the Kuroshio Bend in Luzon Strait 总被引：10，自引：0，他引：10
The mechanism of the anticyclonic eddy's shedding from the Kuroshio bend in Luzon Strait has been studied using a nonlinear
2 1/2 layer model, in a domain including the North Pacific and South China Sea. The model is forced by steady zonal wind in
the North Pacific. Energy analysis is adopted to detect the mechanism of the eddy shedding. Twelve experiments with unique
changes of wind forcing speed (to obtain different Kuroshio transports at Luzon Strait) were performed to examine the relationship
between the Kuroshio transport (KT) and the eddy shedding events. In the reference experiment with KT of 22.7 Sv (forced with
zonal wind idealized from the annual mean wind stress from the COADS data set), the interval of eddy shedding is 70 days and
the shed eddy centers at (20°N, 117.5°E). When the Kuroshio bend extends westward, the southern cyclonic perturbation grows
so rapidly as to form a cyclonic eddy (18.5°N, 120.5°E) because of the frontal instability in the south of the Kuroshio bend.
In the evolution of the cyclonic eddy, it cleaves the Kuroshio bend and triggers the separation of the anticyclonic eddy.
In statistical terms, anticyclonic eddy shedding occurs only when KT fluctuates within a moderate range, between 21 Sv and
28 Sv. When the KT is larger than 28 Sv, a stronger frontal instability south of the Kuroshio bend tends to generate a cyclonic
eddy of size similar to the width of the Luzon Strait. The bigger cyclonic eddy prevents the Kuroshio bend from extending
into the SCS and does not lead to eddy shedding. On the other hand, when the KT decreases to less than 21 Sv, the frontal
instability south of the Kuroshio bend is so weak that the size of corresponding cyclonic eddy is smaller than half the width
of the Luzon Strait. The cyclonic eddy, lacking power, fails to cleave the Kuroshio bend and cause separation of an anticyclonic
eddy; as a result, no eddy shedding occurred then, either. 相似文献
9.
One hundred and ninety-one Argos satellite-tracked drifters deployed at the Luzon Strait in winter during 1991 to 2004 were ana- lyzed to understand the near surface current in northern South China Sea (SCS). Several major track patterns of these drifters have been found. There are: (1)shelf slope landing way (SLW) ; (2)deep basin way (DBW) ;(3) weak loop current pattern; (4) northward movement directly driven by the Kuroshio. These observations show the effects of the basin scale gyre circulation, mesoscale eddies and the Kuroshio on the drifters' ovement. 相似文献
10.
A Review on the Currents in the South China Sea: Seasonal Circulation, South China Sea Warm Current and Kuroshio Intrusion 总被引：47，自引：4，他引：43
Researches on the currents in the South China Sea (SCS) and the interaction between the SCS and its adjacent seas are reviewed. Overall seasonal circulation in the SCS is cyclonic in winter and anticyclonic in summer with a few stable eddies. The seasonal circulation is mostly driven by monsoon winds, and is related to water exchange between the SCS and the East China Sea through the Taiwan Strait, and between the SCS and the Kuroshio through the Luzon Strait. Seasonal characteristics of the South China Sea Warm Current in the northern SCS and the Kuroshio intrusion to the SCS are summarized in terms of the interaction between the SCS and its adjacent seas. 相似文献
11.
黑潮对邻近中国海的影响和琉球海流研究在物理海洋学是一个很重要的、有趣的课题。为了深入地阐明由中国科学家自2010年7月至2015年5月期间所作研究的进展,本文在以下三个方面进行评述。第一方面是关于黑潮入侵南海以及在吕宋海峡周围的环流,分为以下二个很重要论题做阐述:黑潮入侵的季节和年际变化以及黑潮入侵的机制;黑潮对吕宋海峡海流和南海北部环流的影响。第二方面是关于黑潮及其对东海相互作用的变化,分为以下四个有趣的论题来阐述:东海黑潮研究的评述;黑潮入侵东海,水交换以及动力因子;由于黑潮作用营养物质通量在下游增加;从卫星遥感的应用对黑潮入侵东海对陆地物质通量的影响。第三方面,琉球海流与东海黑潮相互作用也被讨论。最后本文主要点作了总结,对今后进一步需要研究也被讨论。 相似文献
12.
Recent progress in studies of the South China Sea circulation 总被引：13，自引：1，他引：12
The South China Sea (SCS) is a semi-enclosed marginal sea with deep a basin. The SCS is located at low latitudes, where the
ocean circulations are driven principally by the Asia-Australia monsoon. Ocean circulation in the SCS is very complex and
plays an important role in both the marine environment and climate variability. Due to the monsoon-mountain interactions the
seasonal spatial pattern of the sea surface wind stress curl is very specific. These distinct patterns induce different basin-scale
circulation and gyre in summer and winter, respectively. The intensified western boundary currents associated with the cyclonic
and anticyclonic gyres in the SCS play important roles in the sea surface temperature variability of the basin. The mesoscale
eddies in the SCS are rather active and their formation mechanisms have been described in recent studies. The water exchange
through the Luzon Strait and other straits could give rise to the relation between the Pacific and the SCS. This paper reviews
the research results mentioned above. 相似文献
13.
Surface current field and seasonal variability in the Kuroshio and adjacent regions derived from satellite-tracked drifter data 总被引：7，自引：2，他引：5
The muhiyear averaged surface current field and seasonal variability in the Kuroshio and adjacent regions are studied. The data used are trajectories and （1/4） ° latitude by （1/4） ° longitude mean currents derived from 323 Argos drifters deployed by Chinese institutions and world ocean circulation experiment from 1979 to 2003. The results show that the Kuroshio surface path adapts well to the western boundary topography and exhibits six great turnings. The branching occurs frequently near anticyclonic turnings rather than near cyclonic ones. In the Luzon Strait, the surface water intrusion into the South China Sea occurs only in fall and winter. The Kuroshio surface path east of Taiwan, China appears nearly as straight lines in summer, fall, and winter, when anticyclonic eddies coexist on its right side; while the path may cyclonically turning in spring when no eddy exists. The Kuroshio intrusion northeast of Taiwan often occurs in fall and winter, but not in summer. The running direction, width and velocity of the middle segment of the Kuroshio surface currents in the East China Sea vary seasonally. The northward intrusion of the Kuroshio surface water southwest of Kyushu occurs in spring and fall, but not in summer. The northmost position of the Kuroshio surface path southwest of Kyushu occurs in fall, but never goes beyond 31 °N. The northward surface current east of the Ryukyu Islands exists only along Okinawa-Amami Islands from spring to fall. In particular, it appears as an arm of an anti- cyclonic eddy in fall. 相似文献
14.
Sources of water in the Taiwan Strait 总被引：5，自引：0，他引：5
The conveyor of the source water that feeds into the Taiwan Strait (TS), particularly from the south, is investigated using
historical CTD (Conductivity-Temperature-Depth) data and a North Pacific Ocean and East Asian seas coupled model. The modeled
currents and drifter trajectories suggest that the Kuroshio Branch Water (KBW) rarely flows directly into the TS from the
Luzon Strait (LS) in winter; instead the massive westward movement of the Kuroshio conveys high salinity water to the southeastern
TS through a loop-like route. In summer, the modeled flow fields suggest that the Kuroshio surface currents hardly intrude
into the TS directly from the LS. Observations and model results show that the monsoon-driven northeastwardflowing currents
in the northern South China Sea transport relatively low salinity water through the entire TS. 相似文献
15.
A method of quantifying the penetration of the Kuroshio into the Luzon Strait is improved with simulated salinity. The new method is applied in an area bounded by 0.6 correlation coefficient contour to the point of 20 N, 118 E which is determined by EOF analysis. The results suggest that the method is suitable for indicating Kuroshio’s intrusion into the South China Sea quantitatively. As an indicator, the Kuroshio penetrating the Luzon index (KLI) reveals obvious annual cycle and weak bimodality. For annual periods, indexes on the surface and subsurface which point the same events have totally opposite signs due to the winter burst of surface westward current. On long-term period, the surface and subsurface indexes have consistent signs. A subsurface index on 150 m avoiding high frequency signals from the surface can be used for indicating long-term Kuroshio intrusion variation. An anti-phase pattern in wavelet coherence map between KLI and Japan large meander index shows that the Luzon Strait is a "smoother" reducing the variability of the Kuroshio transport changes on long-term periods. 相似文献
16.
根据2001年3月份南海东北部航次调查温、盐资料,分析了2001年冬末春初南海东北部温、盐结构和环流的特征.分析结果表明:观测期间南海东北部环流主要受一次海盆尺度气旋型冷环流支配,冷环流呈现双核结构,垂向尺度接近1000 m.吕宋海峡内侧断面的水交换在600 m以浅海水流入南海,在断面南部(20°N以南)中层和深层有流出,断面法向地转流向西净输运量为6.9×106m3/s;直接的黑潮入侵不超过120.5°E,但有部分的黑潮水沿陆坡达到台湾岛西南部海域,并更有一部分逸入东沙岛以西海域,与南海水混合变性. 相似文献
17.
Upper-layer circulation in the South China Sea has been investigated using a three-dimensional primitive equation eddy-resolving
model. The model domain covers the region from 99° to 122°E and from 3° to 23°N. The model is forced by the monthly averaged
European Centre for Medium-Range Weather Forecasts (ECMWF) model winds and the climatological monthly sea surface temperature
data from National Oceanographic Data Center (NODC). Inflow and outflow through the Taiwan Strait and the Sunda shelf are
prescribed monthly from the Wyrtki estimates. Inflow of the Kuroshio branch current in the Luzon Strait is assumed to have
a constant volume transport of 12 Sv (1 Sv = 106 m3/s), and the outflow from the open boundary to the east of Taiwan is adjusted to ensure the net volume transport through all
open boundaries is zero at any instant. The model reveals that a cyclonic circulation exists all year round in the northern
South China Sea. During the winter time this cyclonic eddy is located off the northwest of Luzon, coinciding with the region
of positive wind stress curl in this season. This cyclonic eddy moves northward in spring due to the weakening of the northeast
winds. The cyclonic circulation becomes weak and stays in the continental slope region in the northern South China Sea in
the summer period. The southwest wind can raise the water level along the west coast of Luzon, but there is no anticyclonic
circulation in the northern South China Sea. After the onset of the northeast monsoon winds in fall, the cyclonic eddy moves
back to the region off the west coast of Luzon. In the southern South China Sea and off the Vietnam coast, the model predicts
a similar flow structure as in the previous related studies.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
Using widespread conductivity–temperature–depth (CTD) data in the Philippine Sea and northern South China Sea near the Luzon
Strait together with altimeter data, we identified an intrusion of water from the Kuroshio into the South China Sea (SCS)
through the Luzon Strait in September 2008. The Kuroshio water obviously intruded into the SCS from 20 to 21°N, and existed
mainly in the upper 300 m. The intrusion water extended as far west as 117°E, then looped around in an anticyclonic eddy and
returned to the Philippine Sea further north. The dynamics of the Kuroshio intrusion are discussed using a 1.5-layer nonlinear
shallow-water reduced-gravity model. The analysis suggests that the strong cyclonic eddy to the east of the Kuroshio in September
2008 was of benefit to the intrusion event. 相似文献
19.
Application of LICOM to the numerical study of the water exchangebetween the South China Sea and its adjacent oceans 总被引：8，自引：1，他引：8
1 IntroductionThe South China Sea (SCS) is the largestmarginal sea in the western Pacific (see Fig. 1). It con-nects with the SCS through the Taiwan Strait, with thePacific through the Luzon Strait, with the Sulu Seathrough the Mindoro and Balabac Straits and with theJava Sea and Andaman Sea through the Sunda Shelf(For convenience, here we refer to the section at 1.5°N,Fig. 2). It is shown that the seasonal SCS circulation ismostly affected by the summer/winter monsoon, andthe no… 相似文献
20.
区域性海洋环流数值模式研究及对南海环流与海峡流量的模拟 总被引：2，自引：0，他引：2
基于MOM模式的物理框架,妥善考虑了开边界的物理过程,改造和发展了一个区域海洋数值模式。本模式不仅可以方便地调整开边界条件,使之满足边界的特定物理条件,而且可以方便地做针对性修改,使模式更加可靠。改进后的模式具有MOM模式物理概念明确、公式便于理解、结果便于表达的全部特点,同时克服了MOM模式边界条件不完整、程序不易调整、参数难以改变的缺点。区域性模式比全球模式的计算速度快很多倍,可以成为区域性研究的有效工具。将此模式应用于南海,利用Hellerman＆Rosenstein气候态风应力驱动模式10a,得到与全球模式效果相当的结果。模式模拟结果展现了南海流场的季节特征,在模式分辨率下表现出了多涡结构。根据模拟的流场计算了南海与其它海域的水交换通量。在年平均意义下,外海水通过吕宋海峡进入南海,南海水通过台湾海峡、民都洛海峡和卡里马塔海峡流出南海。各海峡水通量具有明显的季节变化。 相似文献