琼州海峡东部气旋涡的季节和年际变化特征与机制研究

A cold cyclonic eddy located east of the Qiongzhou Strait and southwest of the Pearl River is usually called cyclonic eddy east of Qiongzhou Strait. This eddy makes an important part of the circulation system of the northern South China Sea shelf, and affects the hydrological environment and ecosystem west of Guangdong. Our preliminary work shows that the generation and variation of the cyclonic eddy can affect the westward transport and spreading of the Pearl River diluted water. However, the generation mechanism, variation characteristics of the cyclonic eddy and its effects on the westward transport of the Pearl River diluted water are still unclear due to limited eddy-resolving observation. The present study will construct a high-resolution model system of the northern South China Sea based on FVCOM and analyze observations, to investigate dynamics of the seasonal and interannual variations of the cyclonic eddy. Numerical experiments will be performed to investigate the contributions of wind and background current on the seasonal and interannual variations of the cyclonic eddy, and also reveal the dynamical mechanism. In addition, particle tracking experiments will be designed to examine the influence of the seasonal and interannual variations on the westward transport of the Pearl River diluted water. The research results will enrich our knowledge of the circulation on the northern South China Sea shelf, and strengthen the simulation and prediction ability of hydrodynamics and ecosystem in the northern South China Sea shelf.

在珠江口西南侧，琼州海峡东部海域存在一个气旋式冷涡，通常称之为琼东气旋涡。该涡是南海北部陆架环流系统的重要组成部分，对粤西海域水文生态环境有重要影响。本项目申请人前期工作还发现该气旋涡的生消与强弱变化会影响珠江冲淡水的西向输运路径与扩散范围。然而，由于缺乏长期涡分辨的观测资料，目前尚不清楚该气旋涡季节与年际变化的演化规律与机理，及其对珠江冲淡水西向输运与扩散的影响。本项目拟基于海洋模式FVCOM，构建能分辨南海北部曲折岸线和复杂地形的高分辨率模型，结合现有观测资料，探讨该气旋涡的季节及长时间尺度变化特征；设计系列敏感性试验，来评估背景风场与流场等因素对该气旋涡的季节和年际变化的贡献，并阐明其机理；设计系列质子追踪试验，来揭示该气旋涡的季节与年际变化对珠江冲淡水西向输运和扩散的影响。本项目的研究结果将丰富对南海北部陆架海环流结构的认识，有助于提高对南海北部陆架水文与生态环境的模拟与预测能力。

通过分析在南海西北部海域收集到的观测资料，包括粤西和北部湾近岸的验潮站水位数据，海流数据，温盐剖面数据以及卫星遥感的海表面温度、海面高度等数据，基本确定了琼州海峡东部气旋涡生成时间和大致空间范围。基于无结构网格海洋模型FVCOM，构建了针对南海西北部陆架海的高分辨率三维斜压模型，给出了琼州海峡东部气旋涡的空间结构，并进一步研究了琼州海峡东部气旋涡的基本特征和动力机制。阐明了琼东气旋涡的季节和年际变化特征；揭示了琼东气旋涡的生效机制和影响因子；研究了琼东气旋涡的强弱变化对珠江冲淡水西向扩展和输运的影响等。本项目的研究结果将丰富对南海北部陆架海环流结构的 认识，有助于提高对南海北部陆架水文与生态环境的模拟与预测能力。