海洋中尺度涡旋动力结构与维持机制研究

Mesoscale eddies in china seas have received great concern as they hold large energy and keep actively interaction with around systems. The oceanic eddies play the important role to transfer the mass, heat, momentum and energy inside sea.They provide energy exchange with the other ocean systems which have different temporal and spacial scales. There are eddy motion and eddy shed from and imersal into currents in horizontal level, and there are convection and sensitive heat transfering between deep overturning and eddies, eddies and atmospheric systems at vertical directions. The magnitude of the energy being transferred and exchanged is huge,it is benefitted from the eddy maintaining. The generation mechanisms of eddy are various and their shapes are different,such as cone,bowl and column，etc. During the eddy energy transfering, the eddy shape keeping and function maintainning all depends on the eddy external force mechanism and internal dynamic restriction. It is necessary to study in detail that the quantitative and qualitative response each other between external and internal mechanisms of eddy maintaining. Satellite can provides the sea surface information, the description from numerical modelling is with some intrinsic limitation as its mathmatical features of physic process and parameterization.Thus to quantitative diagnose the eddy dynamic structure by physic experiment will benefit the knowledge extension on feature of eddy in mass transportation and energy equilibrium.The project focus on mesoscale eddy maintainning mechanism and its three dimension structure. According to the comparison of numerical simulation and physic experiment, the statistic validation by data from satellite and ocean invesitgation,to emphasize the energy contribution and transferring by eddies during their maintaining.

海洋中尺度涡旋所含能量巨大,并与其他系统活跃地相互作用而广受关注。海洋涡旋是水体质量、热量、动量和能量输运重要媒介。它们与周围不同时空尺度的系统进行能量交换,水平方向有涡旋移动及与海流的分离与合并,垂直方向上有与深层系统如南半球翻转流及与上层大气系统的对流及感热传递。这些能量交换与传递量级可观,得益于涡旋的持续维持。涡旋不但生成机制不同,形态也多样,如圆锥形,圆柱形,碗形等, 在其能量传输过程中其形态与功能的维持应与其外部强迫机制相关,也与其内部结构的动力约束有关。内外部机制如何定性定量地响应,需要深入探索。卫星观测主要给出海气界面信息,数值模拟因物理过程和参数化的数值性质,对涡动结构描述需要验证,因此以物理实验对涡旋三维结构进行定量化诊断,有助于了解涡旋能量传输特征。本项目关注中尺度涡维持机制与内部结构,运用数值模拟和物理实验对比,卫星与观测资料统计验证,定量化认识涡旋的综合能量贡献。

中国海域的海洋中尺度涡旋已受到广泛关注与大量研究。这些水平尺度通常在几十到几百公里范围，时间尺度在几天、几周到几个月的的涡旋，所含能量，在统计意义上看，总体上比海洋中其他类型运动的能量都大，是海洋水体质量、热量、动量和能量输运的重要媒介，台风引致的海洋涡旋是中尺度涡旋中的具有强度大生命期短的一类。中尺度涡的维持与能量交换与其外部机制的环流系统、陆界形态、海面风况、地转效应等因素有关。中尺度涡活动的季节特征以及对强台风过境的显著响应，显示了诸因子的综合效果。.目前海洋中尺度涡旋研究采用的资料主要有,一是卫星高度计反演的海面高度异常(SSHA)场，需要经计算提取才能表现涡旋环流。二是浮标资料，通常提供局部海域要素，并不反映整体涡旋。三是再分析数据和数值模拟产品，可给出由风应力强迫的海洋涡旋，通常环流模式的流场相对稳定，涡旋形态良好。并且时空精度会优于卫星反演数据。本课题运用卫星反演数据的调查， 区域海洋模式和区域气象模式的数值模拟，辅以物理试验方法和浮标资料检验，重点研究中国东部海域中尺度涡旋统计特征、三维结构，维持机制和能量输送。.项目主要成果为：（1）中国东部海域海洋中尺度涡旋的统计特征。此区域地形复杂， 监测难度大，以往少有海洋中尺度涡旋研究。涡旋特征有别于开阔海域，调查结果具有实际应用意义。（2）涡旋结构的模拟与分析，主要采用数值模拟与物理实验。其中数值模式模拟了典型的海洋涡旋以及分组合成的海洋涡旋，认识活动在该海域的气旋式和反气旋式海洋涡旋的主要三维结构和要素及能量分布特征。物理实验则关注有无旋转科氏力作用以及局地风波流综合效应水体涡旋和近水面气体涡旋的特征。（3）对东部海域的环境强迫因子进行诊断与模拟。获得台风、气旋、锋面、急流、地形、海流等多种强迫对该海域涡旋生命演变的影响作用。. 项目研究工作较为系统，研究内容比较全面，对中国东部海域中尺度涡旋提供良好的深入认识，及丰富的参考信息。