东海对马暖流水来源的数值模拟

本文通过二维数值模拟对1986年6月～1988年12月东海对马暖流水的来源问题进行了初步探讨,结果得出东海对马暖流水的来源基本上分为三种类型:(1)东海对马暖流水主要为东海黑潮水继续北上部分构成;(2)东海对马暖流水由东海黑潮水、东海陆架水以及东海北部黄海大陆沿岸水几部分混合而成;(3)东海对马暖流水几乎全部由东海北部的黄海大陆沿岸水构成。模拟与实测结果基本一致.     

夏、冬季对马暖流（表层）来源的数值模拟

本文利用黄海南部、东海及台湾以东海域表层流分布图提供的资料作为边界条件，对区域１１９°～１３２°Ｅ，２１°～４１°Ｎ做数值模拟．模拟出的流场各流系与实测的基本吻合。所得主要结论为：（１）在３０°～３３°Ｎ，１２５°～１２８°Ｅ这一区域流速小，流向不稳定，它的西、南部分别有流入，东、北部有流出的这一特点与孙湘平所提出的“海水集散”区概念一致、（２）对马暖流不能简单地视为黑潮的分支，应该认为“海水集散区”是它的发源地，此“海水集散区“的水来源是多方面的。     

夏,冬季对马暖流（表层）来源的数值模拟

本文利用黄海南部、东海及台湾以东海域表层流分布图提供的资料作为边界条件，对区域１１９°～１３２°Ｅ，２１°～４１°做数值模拟，模拟出的流场各流系与实测的基本吻合。所得主要结论为：（１）在３０°～３３°Ｎ，１２５°～１２８°Ｅ这一区域流速小，流向不稳定，它的西、南部分别有流入，东、北部有流出的这一特点与孙湘平所提出的“海水集散”区概念一致。（２）对马暖流不能简单地视为黑潮的分支，应该认为“海水集散区     

对马暖流“东海段”的流路与流速

本文全面地分析了此段海流的流路与流速结构，首次提出研究海域近底层的环流示意图。指出在夏季，韩国南岸和日本九州北岸均存在着一支南下的逆流。九州西岸出现两种或多种形式的流路。对马暖流在源地流速很弱，流向不稳定，流路时隐时显不明显，只有离开源地后才逐渐显示出一支海流轮廓；强流区在朝鲜海峡附近。该海流可明显地划分为三段流速夏强冬弱，夏季度幅宽约８０ｋｍ．     

对马暖流“东海段”的流路与流速

本文全面地分析了此段海流的流路与流速结构，首次提出研究海域近底层的环流示意图。指出在夏季，韩国南岸和日本九州北岸均存在着一支南下的逆流，九州西岸出现两种或多种形式的流路。对马暖流在源地流速很弱，流向不稳定，流路时隐时显不明显，只有离开源地后才逐渐显示出一支海流轮廓；强流区在朝鲜海峡附近。该海流可明显地划分为三段。流速夏强冬弱，夏季流幅宽约８０ｋｍ。     

日本海西南陆坡全新世对马暖流演化的沉积学和地球化学记录

对日本海西南陆坡对马暖流主流轴下方高沉积速率沉积物柱状样,进行了沉积学和地球化学系统研究,以探讨全新世以来对马暖流在研究区的形成与演化,并得出了与附近地区古海洋学方法非常相近的结果,从而为今后研究区的对马暖流演化研究提供了沉积学和地球化学指标。据此,该柱状样中所记录的对马暖流演化可划分为5个主要阶段。全新世初期(9.6 kaBP),对马暖流开始进入日本海,其强度较弱,同时,伴随着富营养东海沿岸水的影响,海底环境由还原性向氧化性转变;6.5 kaBP时,对马暖流控制下的日本海南部现代对流模式最终建立起来,东海沿岸水的影响基本消失,随后,对马暖流明显减弱;3.0 kaBP时,对马暖流再次增强并基本达到现在水平,且在随后的3 ka里保持总体稳定,期间在2.0~0.7 kaBP存在一次较弱的减弱过程。     

Kuroshio warm filament and the source of the warm water of the Tsushima Current

Characteristics and evolution of the Kuroshio frontal eddies and warm filaments are analyzed according to two series of satellite images (March 5 to 7, 1986 and April 14 to 16, 1988). The results show that the frontal eddies in the East China Sea are generated at the shelf break and move along the continental slope at a speed of 15 cm/s with the Kuroshio. The frontal eddies occur about every 10 d and evolve to be warm filaments a few hundred km in length and 30-40 km in width in the area west of the Yaku-shima. Meanwhile, the existence of the warm filament was also found in the area by analysing the hydrographic data in the area west of Kyushu during May 24-June 5, 1988.The Kuroshio warm filaments move westward opposite to the Kuroshio and then turn northward at the shelf break and become the main source of the warm water of the Tsushima Warm Current. A simple dynamic explanation for the process is presented in this paper.     

Structure of the Tsushima warm current in the northeastern Japan Sea

By using Acoustic Doppler Current Profiler (ADCP) measurements with the four round-trips method to remove diurnal/semidiurnal tidal currents, the detailed current structure and volume transport of the Tsushima Warm Current (TWC) along the northwestern Japanese coast in the northeastern Japan Sea were examined in the period September–October 2000. The volume transport of the First Branch of the TWC (FBTWC) east of the Noto Peninsula was estimated as approximately 1.0 Sv (10⁶ m³/s), and the FBTWC continued to flow along the Honshu Island to the south of the Oga Peninsula. To the north of the Oga Peninsula, the Second Branch of Tsushima Warm Current and the eastward current established by the subarctic front were recombined with the FBTWC and the total volume transport increased to 1.9 Sv. The water properties at each ADCP line strongly suggested that most of the upper portion of the TWC with high temperature and low salinity flowed out to the North Pacific as the Tsugaru Warm Current. In the north of the Tsugaru Strait, the volume transport of the northward current was observed to be as almost 1 Sv. However, the component of the TWC water was small (approximately 0.3 Sv).     

Seasonal variations of the surface currents in the Tsushima Strait

Seasonal variations of the surface currents in the Tsushima Strait were investigated by analyzing the monthly mean surface currents measured with HF radar. Several new features of the surface currents have been found. One notable feature is the large, complicated seasonal variation in the current structure in the eastern channel of the strait. For example, in the southeastern and northwestern regions of the channel, southwestward countercurrents are found in summer while southeastward acrossshore currents are found in autumn and winter. The wind-driven flow (Ekman flow) as well as surface geostrophic currents are responsible for these complicated variations of the surface currents. To quantify each variation of the flow and current, the wind-driven flow was calculated from the monthly wind (more precisely, the friction velocity) using the monthly speed factor and deflection angle estimated in our previous study, and the surface geostrophic currents were then estimated by subtracting the wind-driven flow from the measured surface currents. It was found that the acrossshore currents are the wind-driven flow, and that the surface geostrophic currents flow almost in the along-shore direction, indicating the validity of the decomposition of the surface velocity into the wind-driven flow and the geostrophic currents using the speed factor and deflection angle. A real-vector empirical orthogonal function (EOF) analysis of the surface geostrophic currents shows a pair of eddies in the lee of Tsushima and Iki Islands as the first mode, which indicates that the southwestward countercurrents in the eastern channel are formed primarily by the incoming Tsushima Warm Current.     

对马海峡环流季节变化的模拟及分析

在利用改进的POM模式的基础上,嵌套西北太平洋区域模式HAMSOM结果,建立1个日本海对马海峡海域斜压准预报模式.通过与已有的观测和研究进行对比,得到较为可信的模拟结果.以温度场和盐度场为参考,系统分析讨论该海域的环流结构及其季节变化.对于温度锋和盐度锋的位置,以及对马暖流的流核等存在争议的问题给出了相应的解释.对马海峡作为日本海的上层水体主要输入区域,对马暖流携带的高温高盐水经过该区域时,在温盐等方面呈现出自南向北的递减变化趋势.对马暖流被对马岛分为东西两支,流核深度随季节变化,并且明显存在双核结构.     

Seasonal variation and formation mechanism of the South China Sea warm water

The South China Sea warm water (SCSWW) is identified as the warm water body withtemperature no less than 28℃ . There are three stages in the seasonal variation of the SCSWW. The SCSWW expands rapidly and deepens quickly in the developing stage. The warm water thickness decreases near the coast of Vietnam and increases near Palawan Island in the steady stage. The SCSWW flinches southward while its thickness off Palawan Island remains no less than 50 m in the flinching stage. The maximum thickness of the SCSWW is always located near the southeastern SCS. The seasonal variation of the SCSWW has a close relationship with seasonal variation of the thermocline. According to the analysis of the numerical experiment results from the Princeton Ocean Model (POM), the mechanism of the seasonal variation of the SCSWW can be interpreted as: (1) in the developing stage, the rapidly expanding and thickening feature of the SCSWW is mainly due to buoyancy flux effect (67% contribution). The weak wind and anticyclonic wi     

POM模式在日本南部黑潮路径变异研究中的应用

日本南部黑潮路径变异对北太平洋地区的气候和环境具有显著的影响,对黑潮路径变异的研究具有重要的意义。本文利用POM(Princeton Ocean Model)数值模式模拟了日本南部黑潮的路径变异情况,分析了黑潮大弯曲路径形成的可能机制。研究结果表明,当黑潮处于非大弯曲路径时,相对位势涡度的平均值呈现递减趋势,说明日本南部低位势涡度水在不断积累,这样会使得四国再循环流的强度增强,迫使黑潮保持平直路径,同时,近岸黑潮垂直流速剪切增大,斜压不稳定性的作用也逐渐增大;当黑潮从非大弯曲路径向大弯曲路径过渡时,再循环流强度的减弱会导致黑潮的流速剪切减小。根据海表高度异常场以及海洋上层流场信息发现,近岸黑潮附近的气旋涡会随着再循环流区域反气旋涡的东侧向南运动,最终导致黑潮大弯曲的发生。分析涡流的能量,结果显示,黑潮大弯曲路径的形成与斜压不稳定性密切相关。     

台湾海峡M_2分潮的三维数值模拟

本文利用普林斯顿海洋模式对台湾海峡 Ｍ ２ 分潮作了分辨率较高的三维数值模拟。在较准确地模拟了潮汐分布的基础上,研究了 Ｍ ２ 分潮流椭圆分析、最大流同时线分布、潮流场的水平及垂直结构,最后还给出了 Ｍ ２ 分潮余流、余水位的分布。结果表明, Ｍ ２ 分潮最大流同时线在海峡中部同时形成密集区和一个圆流点;构成海峡潮波系统的两股潮波中,南支潮波的影响似超出了以往所认为的范围;最大潮流仅在近海底处急剧减小,最大流方向随深度增加右转,到近底层又向左转;潮汐余流和余水位均较弱,仅在澎湖水道、台湾浅滩附近余流较大。     

河流和暖平流对中国东部近海逆温层影响的数值研究

为定量化研究影响中国东部近海逆温层产生和发展过程的主要因素,基于Princeton Ocean Model(POM),通过进行河流和暖流的增减试验,对逆温层的季节变化及其影响因素进行了分析。模拟结果显示,受海表失热影响,逆温层主要出现在9月至翌年3月份,山东半岛北部及东部近海、闽浙沿海为三个主要逆温层发生区域,其中山东半岛北部近海逆温层范围和强度最大。当无河流输入时,整个研究海域无逆温层出现,而河流加倍或减半对逆温层的影响主要体现在长江口邻近海域,出现概率分别增高22%和降低15%。当暖流加倍或减半时,长江口邻近海域逆温层出现概率大幅增高23%和降低69%,山东半岛东部近海次之,分别增高34%和降低25%。当关闭暖流时,长江口外海逆温层消失,山东半岛东部近海逆温层出现概率降低约70%,且变浅76%。以上表明,河流淡水是中国东部近海逆温层形成的必要条件,在保持必要河流淡水输入条件下,暖流的变化对中国东部近海逆温层形成的影响比河流变化大,其中对长江口外海影响最大,山东半岛东部近海次之。暖流流量的增减可引起100 m以浅陆架区的海表面高度异常,影响跨40 m等深线海水交换和温盐锋面的形成,造...     

Structure of the subsurface counter current beneath the Tsushima warm current simulated by an ocean general circulation model

The subsurface counter current beneath the Tsushima Warm Current is simulated using a three-dimensional circulation model. The model well reproduces the counter current beneath the Tsushima Warm Current on the shelf break. The counter current appears as nearshore parts of the subsurface clockwise circulations from spring to early winter. The clockwise circulations are separated by developed shelves such as the Oki Spur and the Noto Peninsula, thus the counter current is not a continuous flow along the Japanese coast in this model. The vertical structure of the counter current can be explained by a density structure with the thermal wind relationship. The permanent and seasonal pycnoclines form mutually opposite horizontal density gradients near the Japanese coast in summer. Such a density structure results in a speed maximum of the counter current away from the bottom. It is remarkable that the second baroclinic mode is dominant in nearshore parts of the subsurface clockwise circulations in summer, which are attributed to the density structure. Similar density structures are also found in some coastal regions of the world oceans where subsurface counter currents are expected.     

台湾海峡西部冬季余流的时空变化

A new data set of observations by six cruises of ship-mounted acoustic doppler current profiler(SADCP) and three 40 d long bottom-mounted ADCPs(BADCPs) is employed to reveal the spatiotemporal variability of tidal and subtidal currents in the western Taiwan Strait(TWS) during winter season. The results confirm the existence of intense cotidal lines for M_2 tidal current, which is located north of 25°N. In this case, no existence of an amphidromic point can be identified. It is also revealed that the counter-wind current(CWC) can extend through the whole western TWS and even occupy the entire water column during winter monsoon relaxation. However,this CWC is observed to be thoroughly overwhelmed by the downwind China coastal current(CCC) during the two big monsoon bloom events in the winter of 2007, and the CCC consequently extends southward throughout the western TWS instead. Most importantly, the variation of the spatial extent for the CWC and the CCC in the western TWS is found to be well explained by the first two modes of the vector empirical orthogonal function(VEOF) analysis, that is, it is mainly controlled by a wind-driven quasi barotropic current as the first mode and slightly modulated by a relatively weak background current with a first-order baroclinic structure as the second mode.