吕宋海峡内潮在西太平洋的长距离传播和演化过程

Luzon Strait (LS) is one of the most energetic generation sites of internal tides (ITs) among world ocean. ITs from LS can radiate both eastward into the Western Pacific (WP) and westward into the South China Sea(SCS). Recent study shows that ITs could propagate over 2500km in the WP, reaching Mariana Ridge; in the SCS, the travel distance could also be over 1600km. Long-range propagation of ITs plays an important role in the energy cascade of multiple-scale dynamic environment of WP and SCS. So far, most studies focused on the propagation process of ITs in the SCS. Due to the lack of field observations, systematic research about the ITs propagation and transformation process in the WP has not been carried out. .Based on field observation data in the WP and LS obtained in recent years, this project aims to study the long-range propagation and transformation process of ITs from LS in the WP through data analysis, numerical simulation, theoretical analysis and remote sensing information extraction. We aim to: reveal the ITs generation process and energy budget in the Luzon Strait; clarify the main propagation branches and paths of ITs; clarify the differences of propagation path between diurnal and semidiurnal ITs and formation mechanism; give the energy budget of other ITs generation sites in the WP; further analyze the mutual interference of ITs from different generation sites and the energy dissipation process; finally probe into ITs’ response mechanism to the background current especially those associated with Kuroshio.

吕宋海峡是全球海洋内潮的最强生成区之一，内潮产生后分别向西太平洋和南海传播，最新研究发现内潮在西太平洋可传播2500多公里，在南海也可传播超过1600公里，其长距离传播过程可在西太平洋和南海多时空尺度动力环境中发挥重要的能量串级作用。迄今的研究大都针对内潮在南海的传播演变开展，但是关于内潮在西太平洋的传播过程和变化规律，受现场观测资料匮乏的限制，尚未有系统的研究开展。.本项目拟基于近年来在西太平洋和吕宋海峡获取的现场观测资料，通过资料分析、数值模拟、理论分析和遥感信息提取相结合的方法针对吕宋海峡内潮在西太平洋的传播演化过程开展研究，首先揭示内潮在吕宋海峡的生成过程和能量收支，明晰内潮在西太的主要东传分支和传播路径，重点理清全日和半日内潮传播路径的差异和形成原因；探明西太其他源区内潮的能量分布，进一步分析多源区内潮的相互干涉和能量耗散过程，探讨内潮传播对背景场变化特别是黑潮的响应过程和机制。

西太平洋是全球内潮最强盛的海域之一，其中由吕宋海峡生成并且向西太平洋传播的内潮能量最为强大。对于吕宋海峡生成的内潮，迄今的研究大都针对内潮再南海的传播演变，而关于内潮在西太平洋的长距离传播和演化过程尚未由系统的研究。本项目采用资料分析、数值模拟、理论分析和遥感资料解译相结合的方法分析了吕宋海峡内潮在西太平洋的生成、传播、耗散及能量收支过程。基于ROMS构建了高精度内潮数值模式，研究了菲律宾海M2内潮生成及长距离能量传递过程，揭示了内潮菲律宾海M2内潮的多源区分布以及多源区内潮长距离传播并相互干涉机制。发现在源区和海盆内部都有显著的内潮能量耗散，内潮的长距离传递在海盆范围对能通量再分配，对海盆局地混合有着显著贡献，该工作被JGR主编推荐为当期亮点文章。结合敏感性数值实验和理论分析，发现地形和层结环境变化对内潮生成有很大影响，在考虑层结的条件下，建立潮-流耦合模式，确证了I-lan海脊和Mien-Hua海底峡谷为内潮的强生成源区，多元内潮相互干涉并且收到黑潮的调制，揭示了台湾东北海域南侧来自I-lan海脊的向南（逆黑潮流动方向）的内潮射线，该研究成果发表于JGR-Oceans。同时，对内孤立波的能量机制进行了实验，分别讨论了背景剪切流不同的特征对二模态内孤立波传播特征和耗散强度的影响，发现二模态波能量耗散的强度和剪切流速差成正比，但和剪切层厚度成反比，证实了二模态在背景剪切流的调制过程中会伴随着强耗散，对跃层附近的混合十分重要，研究成果发表于NPG。本项目培养博士研究生3名，硕士研究生1人，正式发表标注论文6篇，均为SCI收录，其中TOP期刊4篇，1篇被JGR主编推荐为当期亮点文章。