Upper turbulent mixing in the interior and surrounding areas of an anticyclonic eddy in the northern South China Sea (SCS) was estimated from underwater glider data (May 2015) in the present study, using the Gregg-Henyey-Polzin parameterization and the Thorpe-scale method. The observations revealed a clear asymmetrical spatial pattern of turbulent mixing in the anticyclonic eddy area. Enhanced diffusivity (in the order of 10⁻³ m²/s) was found at the posterior edge of the anticyclonic mesoscale eddy; on the anterior side, diffusivity was one order of magnitude lower on average. This asymmetrical pattern was highly correlated with the eddy kinetic energy. Higher shear variance on the posterior side, which is conducive to the triggering of shear instability, may be the main mechanism for the elevated diffusivity. In addition, the generation and growth of sub-mesoscale motions that are fed by mesoscale eddies on their posterior side may also promote the occurrence of strong mixing in the studied region. The results of this study help improve our knowledge regarding turbulent mixing in the northern SCS.

本研究使用Gregg-Henyey-Polzin参数化和索普尺度，根据本研究的水下滑翔机数据（2015年5月）估算了南海北部反气旋涡内部和周围区域的上部湍流混合。方法。观测结果表明，在反气旋涡流区湍流混合的空间格局明显不对称。增强的扩散性（约10 ^-3 m ²/ s）位于反气旋中尺度涡旋的后边缘；在前侧，扩散率平均降低了一个数量级。这种不对称模式与涡动能高度相关。后侧较高的剪切方差可能导致剪切不稳定性的触发，这可能是扩散率升高的主要机制。此外，由中尺度涡流在其后侧馈入的亚中尺度运动的产生和增长也可能促进所研究区域中强烈混合的发生。这项研究的结果有助于提高我们对北部SCS湍流混合的了解。