温跃层位置的透镜状结构对于全球海洋的次表层质量、热量和盐量输运起到潜在的重要作用。尽管透镜状结构在全球其他海域已多有记录，却未曾在中国海被观测到过。项目第四课题首席胡建宇团队报道了2007年9月在南海西南部海域的温跃层位置观测到的一个透镜状结构。该结构最大厚度约60 m，水平范围超过220 km，这比前人研究记录的类似结构都来得大。该透镜状结构核心区的水团属性较为均匀，与周围水体相比，其温度较高（~28.8°C）、盐度较低（~33.3）且位势涡度也较低。基于一套海洋再分析资料，作者通过分析表层和次表层的温盐分布随时间的演化、垂向位涡通量等来研究该透镜状结构可能的形成机制。结果表明，该结构内部的水体很可能来自两个源地：1）局地的混合层水；2）近岸急流离岸位置附近的水体。

Lin, H., Hu, J., Liu, Z., Belkin, I. M., Sun, Z., & Zhu, J. (2017). A peculiar lens-shaped structure observed in the south china sea. Sci Rep.7: 478 | DOI:10.1038/s41598-017-00593-y

Abstract：

Lens-shaped structures within thermocline potentially play a significant role in subsurface transport of mass, heat, and salt in the global ocean. Whilst such structures have been documented in many oceanic regions, none has been observed in the China Seas. This study reports on observations of a lens-shaped structure within thermocline in the southwestern South China Sea in September 2007. This structure had a maximum thickness of approximately 60 m and a horizontal extent exceeding 220 km. This lens
was peculiar in that its size is larger than most similar structures documented in the literature. The lens core was characterized by well-mixed water with higher temperature (~28.8 °C), lower salinity (~33.3) and lower potential vorticity (PV) compared to the surrounding waters. Based on an ocean reanalysis, possible generation mechanism of the lens is explored by examining the evolution of surface and subsurface thermohaline properties, and an analysis of vertical PV flux. The lens was likely generated by
a mixture of the local mixed-layer water and the water from the coastal jet separation site.