中尺度涡旋发展对南海西部环流的动力影响

There are strong meso-scale eddies activity in the western South China Sea, and the western boundary current region in the South China Sea (SCS) is one of the most activity area of meso-scale eddies. The meso-scale can influence the sea surface height and the thermocline variability, by transferring the water, heat and salt fluxes et al. But the details of the dynamics mechanism, how about the eddy influence the western circulation in the SCS, by changing the sea surface height and thermocline are unclear. In this project, the meso-scale eddy variability in the western SCS will be further analyzed in different seasons, and the role of the heat and momentum flux transfer on western circulation in the SCS will be further recognized. From the heat and momentum budgets, we will focus on discussing the space-time variability of the western circulation with different eddy activity, and further reveal the possible dynamic influence mechanism of the meso-scale eddies development on the western circulation in the SCS.

南海西部有着强烈的中尺度涡旋运动，尤其是南海西边界流地区是中尺度涡旋活动活跃区域之一。中尺度涡旋能够通过自身的水体和热盐输送等过程，对海表面高度和温跃层的变化产生直接影响。涡旋是如何通过改变海表面高度变化和跃层动力特征，从而影响南海西部环流动力学的机理尚不清楚。本项目将通过分析不同季节南海西部涡旋的中尺度变化特征和规律，深入认识涡旋热动量输运在南海西部环流调整过程中的作用。通过能量和动量收支，探讨不同涡旋强度下环流变化的时空特征，从而进一步揭示中尺度涡旋发展对南海西部环流的可能动力影响机理。

基于观测数据和数值模拟，证实在中尺度涡西传的过程中，高阶模态不断的向低阶模态转化，由于中尺度涡的自身发展以及自身结构的不对称性诱发出净的跨陆坡流。探讨了越南沿岸南海西边界流夏季涡流相互作用的年际变化特征以及平均流对中尺度过程的贡献。探讨了夏季越南离岸流区域涡-流相互作用特征, 通过能量收支方程诊断评估了风应力、压力梯度、正斜压不稳定以及平流的相对贡献。南海西边界流减弱，在南部海盆形成封闭的气旋涡结构。数值实验与动能收支分析揭示了非局地风与黑潮入侵通过西边界流的平流影响南部环流的变化过程。该项目的开展和成果将拓展对区域物理海洋学的研究认识。