基于卫星遥感和数值模拟的海南岛东南海域内波研究

Spaceborne synthetic aperture radar images acquired in decadal years reveal that the northwestern South China Sea (SCS) is another hot spot of internal solitary waves (ISWs) occurrences, compared with the well-known northeastern SCS. However, the generation, propagation and evolution of internal waves in the northwestern SCS are still yet poorly understood partly because of the limited research works. In this project, we emphasize on studying IWs widely observed in the southeast Hainan Island. Mainly by employing spaceborne SAR data, we will investigate spatial characteristics of IWs in this area and their possible laws. Furthermore, taking advantage of a developed and optimized three-dimensional model built on the MITgcm, three-dimensional characteristics of the nonlinear internal waves will be studied. In conjunction with satellite remote sensing, numerical simulation and field measurements, the project will identify the source sites of the IWs in this area and reveal their lifecycle, that is, from an initial generation with a form of internal tides at source sites, through propagation onto the continental slope and undergoing nonlinear transformation near the shelf-break, and to the final excitation of ISWs on the continental shelf. The outcomes would enrich our scientific insights into the internal waves in the northwestern SCS, and lay a foundation for further investigating their dissipation and mixing.

年代际尺度的卫星SAR数据表明南海西北部是南海北部另外一个内孤立波频发区域，但是针对该海域内波研究较为有限，对其发生、传播和演化的动力学过程和机理研究需要进一步加深。本项目以海南岛东南海域非线性内波为研究对象，以卫星SAR为主要数据源，进一步厘清该区域内孤立波空间特征和规律；通过建立、优化基于MITgcm的数值模式，研究该海域非线性内波的三维特性；综合卫星遥感、数值模拟和现场观测手段，明晰该区域内波产生源区，刻画内潮自源区产生、传播至陆架破折处、再至陆架上演化为内孤立波的动力学过程，从而揭示海南东南海域非线性内波的生成与传播机制，进一步深化对南海西北部内波的科学认知。

本项目的研究目标为阐明海南岛周边海域内波的产生机制和传播过程。通过多源年代际尺度的星载SAR观测、理论分析、星-海协同观测实验和数值模拟，聚焦海南岛东南部和南部海域，获得了这两个海域内波的基本特征，系统地研究了内波的产生和传播机制，建立了内波振幅反演新方法。具体为：在海南岛东南部海域，揭示了西沙群岛作为南海西北部内波的一个新源区，全面地阐明了内波从西沙群岛经海盆、陆坡至中陆架的演变过程和机制；在海南岛南部海域，厘清了内波的空间分布特征，发现了分布在陆架北部和南部的两类内波，揭示了这两类内波的不同产生机制；此外，建立了一种基于时序SAR影像对的浅水海域内波振幅反演方法，解决了用两层流体模型反演内波振幅时，上层流体厚度的不确定性对反演结果产生显著影响的难题。.通过执行项目计划的各项研究内容，本项目基本实现了预定研究目标，相关研究成果发表在国际知名杂志Journal of Physical Oceanography、Journal of Geophysical Research-Oceans和Remote Sensing上，并授权2项国家发明专利。项目成果对于全面认识和理解南海西北部内波的特征和动力学过程具有重要的学术价值。项目成果也已应用到军事海洋环境安全保障。