台湾暖流向岸分支路径的变化特征和机制研究

Carrying the warm and saline water, the Taiwan Warm Current (TWC) intrudes into the continental shelf of the East China Sea (ECS), with the inshore branch (TWCIB) arriving at the outside of Changjiang river mouth. The TWC plays a significant role on the hydrographic structure, circulation, ecosystem and chemical characteristics in the ECS. Substantial work has been carried out to study the source, the hydrographic structure and the intrusion mechanisms of the TWC. While few work focuses on the path and front of TWCIB because lack of observations. By analyzing the collected observed hydrographic and current data, we preliminary found that the front and path of the TWCIB exist seasonal and synoptic variations, that the front may shift meridionally and path could swing zonally. However, the detailed characters and the mechanisms of the variations are unclear. To meet the goal of this project, we plan to define the intrusion path of TWCIB using horizontal gradient of salinity based on hydrographic data, and to study the variations in the intrusion path. At the meantime, we are going to set up a numerical model too, which will perform actual experiments and sensitivity experiments to study the mechanisms of the variations. By combining these methods, we aim to clarify the variations in path and front of TWCIB and mechanisms of the variations in detail. To carry out this project, we are going to improve the understanding of variations in TWCIB which can also help to study the mechanisms of relevant ecological disaster.

台湾暖流携带高温高盐外海水入侵到东海陆架区，其向岸分支可到达长江口外。台湾暖流向岸分支的变化对我国近海温盐分布、环流特征及生态灾害爆发具有重要影响。前人对台湾暖流上游区域开展了大量研究，对其来源、温盐特征及入侵机制取得重要研究成果，而对台湾暖流下游，即向岸分支流轴及前锋的变化认识模糊。通过分析积累的温、盐数据和潜标长时间观测，申请人初步发现，台湾暖流向岸分支存在季节尺度和天气尺度的变化，流轴存在摆动，前锋的北界也存在变化，但对其详细特征和变化机制尚不清楚。本项目立足于观测数据，提出应用盐度梯度法确定台湾暖流向岸分支路径，并探讨其变化特征；结合数值模拟进行实际实验和敏感性实验，研究台湾暖流向岸分支路径变化对驱动因素的响应过程和其变化机制。本项目旨在详细阐明台湾暖流向岸分支流轴及前锋的变化特征并揭示其变化机制。项目的实施有利于完善对台湾暖流向岸分支的认识，有助于研究相关海域生态灾害的机理。

台湾暖流携带高温、高盐、高营养盐、低氧特征的外海水入侵到东海陆架区，其向岸分支可入侵到长江口外。台湾暖流向岸分支的变化及混合特征对其流经海域特别是长江口附近的生态灾害存在重要影响温盐分布、环流特征及生态灾害爆发产生重要影响。前人对台湾暖流上游区域开展了大量研究，对其来源、温盐特征及入侵机制取得重要研究成果，而对台湾暖流入侵前锋的范围及变化研究较少，对其变化特征认识不够详细，对其变化机制尚不明确。本项目应用CTD观测资，ADCP以及微结构湍流剖面仪观测，结合数值模拟开展台湾暖流向岸分支变化及其混合特征的研究。通过分析积累的温、盐数据和潜标长时间观测，我们发现发现台湾暖流底层水对西南黄海存在影响，此影响可以超过32°N。其最北影响范围及流轴摆动存在季节变化，且主要由季风引起的正压调整影响。应用底层盐度梯度的方法研究黑潮底层分支对长江口海域入侵路径的变化特征。其路径存在冷半年离岸向北，暖半年近岸偏南的摆动。主要受季风影响，东北风有助于黑潮底层分支主轴离岸，向北运动，其向岸转向点位置偏北，西南风起到的作用相反。通过本项目研究我们详细阐明台湾暖流向岸分支流轴及前锋的变化特征并揭示其变化机制。此外，通过本项目的研究，我们阐明了台湾暖流与长江冲淡水共同作用下的长江口湍流混合分布特征合机制。项目的完成有利于完善对台湾暖流向岸分支的认识，有助于研究相关海域生态灾害的机理。