【作者】 郑沛楠；

【导师】 吴德星； 杨嘉岩； 林霄沛；

【作者基本信息】 中国海洋大学 ， 物理海洋学， 2009， 博士

【摘要】 黑潮是北太平洋上一支最强的西边界流，具有高温、高盐、流幅窄、流速快、流量大的特征。黑潮的季节和年际变化会对气候产生重大影响，对东亚陆架海域的能量、动量和热量的变化，大中尺度过程的相互作用等都有重要的作用。研究黑潮对东亚陆架海域的作用问题，是深入了解大洋环流变化对陆架海影响的关键，具有重要的科学意义和现实意义。日本海是西北太平洋上的重要海域。该海域作为一个边缘海与中俄朝韩日五国陆地领土接临，周边有诸多重要军事港口，其战略地位的重要性不言而喻。本文在回顾前人研究的基础上，以对马暖流为研究主线，通过资料分析、理论推导结合数值模拟结果分析，重点研究了黑潮对日本海边界环流的影响机制；黑潮在年际变化尺度上对日本海环流的影响等。日本海存在北向流动的东、西两支边界流。本文提出：黑潮北上流动所造成的南北方向的压力差为这两支边界流的主要驱动力；提出绕岛积分约束、位涡收支积分约束和质量守恒约束是形成和维持日本海北上东、西边界流的主导动力学机制的猜想。利用POM模式，建立了西北太平洋环流场。在模式验证合理的基础上，基于绕岛积分约束和位涡收支积分约束以及质量守恒约束，解释了对马暖流进入日本海后分东、西两支边界流的机制问题。研究认为，进入日本海的对马暖流的流量及其季节变化主要受制于大洋过程，而非日本海局地效应造成。自对马海峡流入日本海的水体，经津轻和宗谷海峡流出日本海，满足质量守恒约束。由于黑潮沿日本岛东岸北上流动，在对马海峡和津轻海峡之间设定了压力差，该压力差为对马暖流的主要驱动力。根据绕岛积分约束，在日本岛的西岸同样感受到此压力差异，加之沿岸地形效应，维持了对马暖流东分支。而关于日本海内的西边界流(通常称之为东韩暖流)，我们用位涡收支积分约束来解释。进入日本海的位涡通量包括地形β效应和行星β效应两部分，计算结果显示进入日本海的净位涡通量为负值。沿岛屿边界位势涡度积分需要正的位势涡度来平衡流入日本海的负位势涡度，这就需要沿朝鲜半岛东岸的边界摩擦力提供正的位势涡度——只有一支强的顺时针北上的西边界环流才能做到这一点。在机制研究的基础上，本文进一步研究了在黑潮年际变化情况下，对于日本海环流的影响。利用适合大洋的混合坐标模型HYCOM，成功模拟了黑潮的10年际逐月变化情况。在此基础上，基于绕岛积分约束和质量守恒约束，研究了黑潮在存在大弯曲和不存在大弯曲的情况下，对对马暖流进入日本海内的东边界流(日本海近岸分支流)的影响机制，结果表明：日本以南黑潮流量与日本海近岸分支流的流量存在良好的正相关关系。当黑潮不存在大弯曲时，日本海近岸分支流强；当黑潮存在大弯曲时，日本海近岸分支明显减弱。对马暖流作为日本海的唯一入流，对日本海的环流、温盐度分布等海洋物理过程具有重要影响。通过改进的POM模式，嵌套了西北太平洋的HAMSOM模式，建立日本海对马海峡海域斜压准预报模式，对对马海峡温盐场以及环流场进行高分辨率的数值模拟。模拟结果显示：对马暖流遇对马岛阻隔，分为东西两支进入日本海，两支海流均存在流核。对马暖流季节变化明显，随着对马暖流的季节变化，流核的位置和强弱均发生变化。对马暖流在东水道流速比西水道流速大。对马暖流携带的高温高盐水从对马海峡流入日本海，与当地冷水团相互作用产生对马海峡处的海洋锋。海洋锋存在于济州岛和对马岛之间，四季皆存在，而且有明显的季节变化特征。春夏季锋面强于秋冬季。对马暖流的来源一直众说纷纭，未有定论。是否存在台湾-对马暖流系统?基于POM模式，设计数值实验论证台湾暖流和对马暖流的动力关系。研究结果进一步验证了“台湾-对马暖流系统”的存在。初步解释了台湾暖流水流向何处以及对马暖流水的来源问题。通过数值实验发现，在该系统中对马暖流扮演更为重要的角色。而台湾暖流的改变对对马暖流影响甚微。能量通过地形波传导理论可能为这一动力学机制的合理解释。更多还原

【Abstract】 Kuroshio Current (KC) is the strongest west boundary current in the East Asian marginal seas (EAMS) . Study on the influence of KC to EAMS is the key point of understanding the ocean circulation effect on the marginal seas, and it has an important scientific and realistic meaning. Japan/East Sea (JES) is an important area of the EAMS. This area acts as a marginal sea connecting the land territory with China, Russia, North Korea, South Korea and Japan. The importance of strategic location is self-evident. Based on the previous studies, this thesis focuses on KC’s influence to the boundary circulation in JES, through data analysis, theoretical derivation and numerical simulation.There are both west and east boundary currents flowing northword in JES. In this thesis, we consider that the preesure difference set by KC is the main forcing of these two boundary currents; the Insland integral constrant, the Potential Voticity (PV) integral constraint and the Mass conservation constrant are the leading dynamic mechanism on forming and mataining these two boundary currents.Based on the POM model, the NWPO circulation field is established. After model validation, the Island intergral constraint, PV integral constraint and Mass conservation constrant are introduced to explain the mechanism for the bifurcation of the Tsushima Warm Current (TSWC) into the JES. Study indicates that the volume transport of TSWC and its seasonal changes are mainly decided by open ocean process, not by the local forcing. KC flows northward along the east coast of Japan Island, sets the pressure difference (Δp) between the Tsushima Strait (TS) and Tsugaru Strait (TSS). And thisΔp is the main force of the TSWC. The water mass flows into JES through TS and flows out of JES through TSS and Soya Strait respectively. It follows the Mass conservation constrant. According to the Island intergral constraint, the west coast of Japan Island is also feels thisΔp, combines with the friction along the west coast of Japan Island, and maintains the east branch of TSWC (named Nearshore Branch, NB) .About the west branch of TSWC, it is explained by the PV integral constraint. In a semi-closed basin, the PV integral over the whole basin yields a balance between the net lateral PV inflow and the PV dissipation along the boundary. The net lateral PV inflow into the JES includes two parts: one is topographyβeffect; the other is the planetaryβeffect. The net PV advection into the JES is negative due to both bathymetrical and latitudinal differences among three straits. A frictional torque associated with a strong anti-cyclonic boundary current is required in order to balance the PV integral constraint along the boundary of JES, and this leads to the establishment of the anti-cyclonic western boundary current.On the basis of the study on mechanism, this thesis further studies the KC inter-annual variability to the JES circulation. Using the hybrid coordinates ocean model (HYCOM), the KC’s monthly variations in 10 years is successfully simulated. The Island intergral constraint and Mass conservation constrant are introduced to study the mechanism of NB in interannual variability, under the situations of the KC’s axis exist the large mender (LM) or non-large-meander (nLM) path. The results show when KC’s axis has the LM, the NB is weaker; otherwise, when KC’s axis has the nLM, the NB is stronger.The TSWC acts as the unique inflow in JES, it plays a significant role on the JES’s physical process. Based on an improved POM, nesting the output of HAMSOM model, a baroclinic quasi prognostic model is built at the TS in JES. The results show that the current advects into the JES through the TS is divided into two parts by Tsushima Island. The main axis of the current at the TS obviously has double-core structure and they seasonally change their depths. The sea front exits all the season.Based on the POM, this thesis establishes several numerical experiments to study the dynamic relationship between TSWC and Taiwan Warm Current (TWC) . The research validates the existence of "TSWC-TWC system" further more. Preliminary find the source of TSWC and where TWC flows. TSWC is more important in this system, and TWC has little effect on TSWC. The possible mechanism can be explained here in terms of energy propagation by topographic waves.更多还原