遥感和观测数据显示，冬季浙闽沿岸流在东山外海形成离岸流，使浙闽沿岸水东扩到台湾浅滩北侧并极大地削弱浙闽沿岸水往南的输运量。对这支离岸流的研究还末见报道，其离岸的时空规律、机制以及产生的环境动力条件是本项目的研究重点。观测表明在东山外海东北季风的变化可以造成南北反向的沿岸水位梯度异常及沿岸流南北向的调整，这些异常及调整是邻近海域水文动力变化的表征，其与离岸流及附近流系的演变有着密切的关联。本课题研究以此为切入点，研究该离岸流的动力机制。课题拟采用东山外海的地波雷达、浮标，潮位站所监测的长时间序列资料，结合遥感数据分析、补充现场航次调查，通过三维海洋模型实验及诊断，动力理论分析对该离岸流的规律及机理进行剖析和研究。该研究是物理海洋在多流系交汇、浅滩陆坡等复杂地形条件下近岸动力学的典型案例，成果将为东海向南海及跨陆架生物地球化学迁移过程提供物理背景及动力依据。

Satellite and in-situ data show part of the China Coastal Current deflects offshore off Dongshan (Southern Taiwan Strait) in winter, which makes coastal water spread off-shore to the shelf and greatly weakens the along-shore volume transport of coastal current. There have not been any studies of the phenomenal reports and mechanism investigation of this off-shore flow. This proposal is going to study its spatial and temporal variations, dynamics mechanism, and occurrence conditions. Our preliminary results show that the northeasterly wind induces a reversed along-shore sea level gradient anomalies over the bank area to the north and south of Dongshan through a change of along-shore coastal current. The along-shore sea level anomalies, as a surface feature of the varied flow dynamics, has a deep link with the off-shore flow and adjacent flow dynamics adjustment to the varied winds and topography. Starting from this idea, this research plan to use a set of equations to study the dynamics of this off-shore flow. The historic time series data of HF radar, buoy, gauge station, remote sensing and in-situ will be collected and analyzed. Combining with the three-dimensional ocean model experiments and dynamical theory analysis, the offshore flow dynamics and mechanism will be well studied. This study can be a special case for the off-shore current in a shallow bank with two reversed flows under the influence of varied winds. The results of this study can provide physical and dynamic explanations for the biogeochemical along-shore transport from the East China Sea to the South China Sea and cross-shelf transport from coastal area to the shelf region.