中文摘要：

中尺度涡是重要的海洋学现象，它在很大程度上影响着海洋内部的能量传递过程．由于传统海洋学观测手段的固有局限性，一直以来对中尺度涡观测和研究的程度都比较低．地震海洋学的诞生和发展为海洋学观测提供了一个全新的手段．对南海的历史地震数据重新处理后，我们首次在本研究海域的地震剖面上看到了透镜状结构．它位于南海西南次海盆（～113．6°E，11．4°N），中心深度约为450m，中心厚度约为300m，半径约为55～65km，具有典型的中尺度涡特征，综合解释为反气旋．我们利用地震海洋学方法估算了地转剪切，结合来自于卫星高度数据的海表面地转流速度进一步得到了绝对流速的垂向剖面．结果显示，流速的最大值约为0．7m／s，出现在400～450m处，对应于涡旋的中心深度；西北部分为正，东南部分为负，整体呈现出顺时针的转动方向，说明了它是一个反气旋结构．

英文摘要：

Mesoscale eddy is an important oceanographic phenomenon which significantly affects the whole oceanic energy budget. Due to the inherent limitations of traditional oceanographic observation methods, the degree of observations and research of mesoscale eddy has been relatively low. Seismic Oceanography, a new interdisciplinary subject of reflection seismology and physical oceanography, provides a new approach for oceanographic observations. After reprocessing of a legacy seismic data acquired in the South China Sea, a lens-like structure was detected for the first time in this region from seismic profiles. It is located in the Southwestern sub-basin of South China Sea （~113.6°E, 11.4°N） with the equilibrium depth of about 450 m, center thickness of about 300 m and radius of 55~65 kin, showing typical characteristics of a mesoscale eddy. With the additional information of sea level anomalies （SLA） and sea-surfacegeostrophic mesoscale e current from AVISO, ddy. Geostrophic shear the lens-like st was also estimat Absolute values of geostrophic velocity a known level, i.e. sea surface values f geostrophic velocity is about 0.7 m corresponding to the equilibrium depth southeast part is were determi rom AVISO. ructure was Interpret ed using the seismic o ned by integrating the The results show that /s, distributed in ~ Of this eddy, the negative, showing a clockwise rotation anticyclonic structure. ed as an anticyclonic ceanographic method shear over depth from the maximum value of the depth range of 400~450 m, northwest part is positive while the as a whole, indicating that it is an