西北太平洋复杂地形下内潮能量辐射途径和耗散机制

The complex topographic features make the northwestern Pacific being one of the most energetic internal tide sources among global oceans. Typical abyssal topographic features, such as the Luzon Strait, the Ryukyu Island chains and the Mariana Arc are all robust source sites. The radiation distance of internal tidal energy could reach over thousands of kilometers in the open ocean. During propagation, the internal tides could be modulated by the background flows associated with the Kuroshio and eddy and exchange the energy among them. The diapycnal mixing induced by internal tide dissipation plays a critical role in the basin-scale water mass exchange and circulation variations. Therefore, the radiation and dissipation processes of internal tide energy under complex topographic conditions should be a key issue of the Major Research Plan which focus on the energy cascade and balance of multi-scale processes. .Based on field data analysis, numerical simulation and theoretical study, this project aims to investigate the life cycle of internal tide radiation and source-sink distributions in the northwestern Pacific, compare the generation processes and mechanisms under different bottom conditions between diurnal and semidiurnal internal tides, reveal the long-range radiation paths and patterns of internal tidal beams modulated by multi-wave interference, clarify the hot spots and mechanism of internal tide dissipation under the subtidal currents and evaluate the contribution of tidal mixing on the water mass distribution and circulation variations. The anticipated results could provide new ideas for improving parameterization scheme in OGCM, and exploit new research space for understanding oceanic dynamical processes and climate variability.

西北太平洋因复杂多变地形的存在而成为全球最强内潮生成区之一，典型深海地形如吕宋海峡、琉球群岛和马里亚纳岛弧均是强内潮源区，内潮可以往远区辐射能通量达数千公里，并受到低频背景场如黑潮、涡旋影响而发生演变及能量交换，同时内潮耗散引起的垂向混合会影响海盆范围内的水团交换和环流变异。因此，复杂地形下内潮能量如何辐射和耗散，是本重大计划多尺度过程能量平衡串级关键且亟需解决的一环。 .本项目以西北太平洋多源区内潮整个生命周期的能量传递耗散和源汇分布为研究目标，采用资料分析、数值模拟和理论研究手段，分析不同地形条件下全日和半日内潮的生成过程和机制差异，揭示多源区内潮射线干涉对长距离辐射路径和形态的影响，探明低频背景流调制下内潮耗散主要发生区域及机制，评估潮致混合对水团分布及环流变异的贡献。预期成果可为改进海洋模式次网格过程参数化方案提供新思路，为理解复杂地形下海洋动力过程和气候变化开拓新的研究空间。

西北太平洋因复杂多变地形的存在而成为全球最强内潮生成区之一，典型深海地形如吕宋海峡、琉球群岛和马里亚纳岛弧均是强内潮源区。复杂地形下内潮能量如何辐射和耗散，是本重大计划多尺度过程能量平衡串级关键且亟需解决的一环。. 本项目以西北太平洋多源区内潮整个生命周期的能量传递耗散和源汇分布为研究目标，构建了西北太平洋关键区域高分辨率内潮数值模型，研究了台湾东北海域M2内潮在黑潮调制作用下能量收支和传播演化过程，确证了I-Lan海脊和Mien-Hua海底峡谷为内潮强生成源区；系统揭示了西北太平洋复杂地形区域多个内潮源区能量转化率、能量通量及局地耗散分布；改进线源波动模型和波射线追踪模型，量化对比了多动力因子对内潮路径的调制机制和贡献；明确了吕宋海峡三种黑潮入侵模态与内潮能量场的动力关联机制。发现黑潮通过平均流而不是层结梯度调制内潮能量场分布格局，拟定了一个具有全球海洋普适性的表征环流与内潮动力能量关联机制的理论判据。首次揭示马里亚纳海脊-海沟区内潮的能量传递过程和耗散分布，提出马里亚纳海沟是内波能量汇的科学观点，将海洋内波动力学研究的视野拓展到海斗深渊。系列研究成果发表于本学科TOP期刊JGR-Oceans。本项目培养毕业博士研究生3名，硕士研究生1人。发表标注论文9篇，其中SCI收录8篇，TOP期刊5篇，2篇文章被选为AGU推选论文、JGR-Oceans高引论文。项目负责人入选2021年度国家高层次人才特殊支持计划青年拔尖人才。