黑潮延伸体时变正压动力过程和动能串级研究

本文基于坐底式逆向回声仪(current and pressure recording inverted echo sounder, CPIES)实测海底压强和海底流速数据对黑潮延伸体时变正压动力过程和动能串级进行研究。先对CPIES数据进行去噪、网格化、调平等预处理,获得黑潮延伸体正压动力高度网格和海底流速网格,后进一步计算得到正压动力高度分布图、正压涡动能分布图以及正压动能通量谱。结果表明:1)在无外力作用时,正压动力高度起伏会使海水从动力高的地方向低的地方流入从而产生较高的涡动能,而一旦有外力强迫,海水有从动力高度低的地方向高的地方流入的可能,从而使得正压动力高度不断增加涡动能增强;2)通过分析9个月长时间平均正压动能通量谱,验证了地转湍流理论中的正压反向动能串级; 3)对黑潮延伸体月平均正压动能通量作谱分析发现,涡动能的大小会影响动能通量幅值变化,当涡动能升高,动能通量谱振幅变大,正向/反向动能串级增强,反之亦然。此外,正压动能串级随着时间变化,表现为2004年6月至8月反向动能串级尺度向小尺度移动并且强度增强; 2004年9月反向动能串级突然减弱,2004年9月至11月出现了...

Investigating the time-varying barotropic dynamic process and kinetic cascade of the Kuroshio extension

In this study, the time-varying barotropic dynamic process and kinetic energy cascade of the Kuroshio extension body were investigated according to the measured seabed pressure and seabed velocity data of bottom-seated reverse echocardiography (CPIES). First, the CPIES data were pre-processed using denoising, gridding, and leveling to obtain the barotropic dynamic height grid and the bottom velocity grid of the Kuroshio extension body. Subsequently, the barotropic dynamic height distribution map, the barotropic vortex kinetic energy distribution map, and the barotropic kinetic energy flux spectrum were calculated. The results revealed that: 1) in the absence of an external force, dynamic height fluctuation of the positive pressure will cause the water to flow from high-power to low-power regions, resulting in the generation of higher eddy kinetic energy. In the presence of an external force, the water flows from the low-power region to the high-power region, increasing the barotropic dynamic height and the eddy kinetic energy. 2) Through analysis of the average barotropic kinetic energy flux spectrum over a long period of nine months, the barotropic reverse kinetic energy cascade in the geostrophic turbulence theory was verified. 3) The spectral analysis of the monthly average barotropic kinetic energy flux of the Kuroshio extension showed that the magnitude of the vortex kinetic energy will affect the variation in the kinetic energy flux amplitude. With increasing vortex kinetic energy, the amplitude of the kinetic energy flux spectrum increases, and the forward/reverse kinetic energy cascade increases, and vice versa. Furthermore, the cascade of barotropic kinetic energy changes with time. From June to August 2004, the cascade scale of reverse kinetic energy reduced, and its strength increased over time. In September 2004, the intensity of the cascade of reverse kinetic energy suddenly weakened, and from September to November 2004, a cascade change process of reverse kinetic energy was similar to that from June to August 2004. Lastly, from December 2004 to January 2005, the forward kinetic energy shifted from the cascade scale to a small scale, and its intensity weakened.