The Seychelles-Chagos Thermocline Ridge (SCTR) is a key region which plays a major role in various regional climatic processes at all time scales. The vertical mixing at the base of mixed layer may be climatically important at this region, where a shallow thermocline and highly variable wind activity exists. In this study, we provide evidence of strong vertical mixing at the base of mixed layer and thermocline associated with near-inertial waves (NIWs) using the microstructure profiler time series data during boreal summer 2014. During the study, it was observed that the surface turbulent layer was mostly confined in the mixed layer with turbulent kinetic energy dissipation rate of the order of 10⁻⁶ Wkg⁻¹. Elevated dissipation rate in the order of 10⁻⁷–10⁻⁶ Wkg⁻¹ was also observed at the base of the mixed layer and thermocline (60–100 m) during the entire period of observation. The estimated vertical diffusive heat flux across the mixed layer base (100 Wm⁻²) was strong and a moderate downward flux (~ 30 Wm⁻²) was noticed in the thermocline region. The analysis showed that the strong NIW triggered by a strong wind event were responsible for the high dissipation rate at the base of mixed layer and at deeper depths. The higher-mode NIW create elevated vertical shear at the base the mixed layer, which leads to the enhanced mixing. The study also showed the possible role of internal tides on the subsurface mixing in the region. The NIW-induced mixing may have important role on the mixed layer heat balance in a climatically active SCTR.

塞舌尔－查戈斯热跃脊（SCTR）是一个关键地区，在所有时间尺度上的各种区域气候过程中都发挥着重要作用。在存在浅温跃层和高度变化的风活动的区域，混合层底部的垂直混合在气候上可能很重要。在这项研究中，我们使用微结构分析仪时间序列数据，在2014年夏季的夏季提供了与近惯性波（NIW）相关的混合层和温跃层底部强烈垂直混合的证据。在研究过程中，观察到表面湍流层主要被限制在混合层中，湍动能耗散率约为10 ^-6  Wkg ^-1。耗散率升高，约为10 ^-7 –10在整个观测期间，在混合层和温跃层（60–100 m）的底部也观测到了^-6 Wkg ^-1。估计的穿过混合层基底的垂直扩散热通量（100 Wm ^-2）强而中等的向下通量（〜30 Wm ^-2）出现在温跃线区域。分析表明，由强风事件触发的强NIW导致了混合层底部和更深深度的高耗散率。高模态NIW在混合层的底部产生较高的垂直剪切力，从而增强了混合效果。研究还显示了内部潮汐可能对该区域的地下混合作用。NIW引起的混合在气候活跃的SCTR中可能对混合层的热量平衡起重要作用。