In the southern Yellow Sea (SYS) there are temperature and salinity inversions associated with the presence of middepth low temperature and salinity water. Many questions regarding with the inversions, such as the seasonal variation and transformation mechanism, still remain unexplained. In this study, based on hydrographic measurements obtain from 12 cruises within 6-year (2017–2022), we explored the distribution, seasonality, generation, and transformation mechanism of temperature and salinity inversions in the SYS. Observations reveal widespread temperature and salinity inversions in the Yellow Sea (YS) during both spring and summer. More temperature and salinity inversions are found in spring and summer, respectively. The relative motion between the fresh, cold, high-dissolved-oxygen (DO) water at the local shelf/slope and the salty, warm, low-DO water at the central trough is the key to answering the formation of temperature/salinity inversions. The salinity at the low-salinity water (LSW) layer increases towards the central YS suggesting the origin of LSW at the local shelf/slope region. Assuming the gain of salinity is caused primarily by vertical diffusion at the upper and lower boundary of the LSW, the propagation speed of the LSW lense is estimated which compares favorably with the magnitude of observed residual currents at the LSW layer. We further note that the depth of subsurface dissolved oxygen maximum agrees well with the LSW layer depth, especially for summer. The influence of the lateral transport of nutrients, and dissolved oxygen on the local biogeochemical environment in the YS is worth further examination.

中文翻译：

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南黄海温盐反演的分布、季节和水体转换

在南黄海（SYS），存在与中深低温和盐度水的存在相关的温度和盐度反转。有关反演的许多问题，例如季节变化和转换机制，仍然无法解释。本研究基于6年（2017-2022）12次航次的水文测量数据，探讨了南海系统温盐反演的分布、季节性、产生和转化机制。观测结果显示，春季和夏季黄海 (YS) 出现广泛的温度和盐度倒转。春季和夏季分别出现更多的温度和盐度倒转。局部陆架/斜坡处的新鲜、冷、高溶解氧（DO）水与中央槽的咸、暖、低溶解氧（DO）水之间的相对运动是回答温/盐度倒转形成的关键。低盐度水 (LSW) 层的盐度向中央 YS 方向增加，表明 LSW 起源于当地的陆架/斜坡区域。假设盐度的增加主要是由 LSW 上下边界的垂直扩散引起的，则估计 LSW 透镜体的传播速度，该速度与在 LSW 层观测到的剩余电流的大小相当。我们进一步注意到，地下溶解氧最大值的深度与 LSW 层深度非常吻合，特别是在夏季。营养物质和溶解氧的横向输送对黄海区局部生物地球化学环境的影响值得进一步研究。