反向动能级串的全球分布特征，各向异性特征及其在涡平衡过程中的作用

发布时间：2018-05-20 15:37

本文选题：能量级串 + 中尺度涡　；参考：《中国科学院研究生院(海洋研究所)》2016年博士论文

【摘要】：海洋观测表明,海洋中90%的动能以遍布大洋的中尺度涡形式存在,这些水平尺度从几十公里到几百公里不等的涡旋普遍存在于绝大部分海域。而中尺度涡的产生过程和平衡过程仍是值得探讨的问题。卫星高度观测到的反向动能级串级串为理解中尺度涡的发展平衡过程提供了一个新的视角。本文使用多种数据集对反向动能级串的全球分布特征,随深度的变化特征和各项异性特征进行了研究,以期对反向动能级串及其在涡平衡过程中的作用有一个更深刻的认识。论文主要结果如下:一、利用卫星高度计海平面高度数据,结合涡分辨率的模式输出数据和再分析数据,讨论了反向动能级串的全球分布特征,特别是反向动能级串的振幅,能量注入尺度和反向传递的动能开始捕捉的尺度。发现在赤道外地区,反向动能级串是普遍存在的,其主要分布100-500km的尺度带上,其振幅和特征尺度表现出显著的区域差异性。二、通过将局地线性斜压理论的预测结果以及观测到的中尺度涡场特征与反向动能级串的特征尺度进行对比,发现反向传递的涡动能主要来源于斜压不稳定过程释放的有效位能,而非线性的反向动能级串将该涡动能向更大尺度传递,对涡动能重新进行分配,并最终达到一个统计稳定状态。即反向动能级串是架起线性理论预测的涡特征尺度和实际观测到的涡特征尺度之间“gap”的桥梁。三、通过诊断反向动能级串随深度的变化特征和各向异性特征,探究反向传递的动能的汇。初步结果表明,在高涡动能的东向强流系,一部分反向传递的动能向下传递。与此同时,一部分反向传递的动能转化为纬向平均流的动能。然而两种能汇各自的贡献仍有待于进步研究。四、使用反向动能级串研究的相关方法,探究了黑潮延伸体区域中尺度涡场的年代际变化特征和产生机制。结果表明,斜压不稳定不是黑潮延伸体中尺度涡场年代际振荡的控制机制,正压不稳定对中尺度涡场的年代际振荡有积极的贡献。而非线性反向动能级串在决定黑潮延伸体中尺度涡场的空间特征方面起了决定性作用。
[Abstract]:Ocean observations show that 90% of the kinetic energy in the ocean exists in the form of mesoscale vortices in the ocean. However, the generation process and equilibrium process of mesoscale vortices are still worth discussing. The reverse kinetic energy levels observed at satellite altitude provide a new perspective for understanding the equilibrium process of mesoscale vortices. In this paper, the global distribution characteristics of reverse kinetic energy order series, the variation characteristics with depth and the heterogeneity of the reverse kinetic energy order are studied by using various data sets, in order to have a deeper understanding of the reverse kinetic energy level and its role in the vortex equilibrium process. The main results are as follows: first, using satellite altimeter sea level height data, combined with vortex resolution model output data and reanalysis data, the global distribution characteristics of reverse kinetic energy level series, especially the amplitude of reverse kinetic energy level series, are discussed. The scale at which the energy injection scale and the kinetic energy transferred in reverse begin to capture. It is found that the reverse kinetic energy cascade is ubiquitous in the region beyond the equator, and the amplitude and characteristic scale show significant regional differences. Secondly, by comparing the predicted results of the local linear baroclinic theory and the observed mesoscale vortex field with the characteristic scale of the reverse kinetic energy cascade, It is found that the vortex kinetic energy is mainly derived from the effective potential energy released by the baroclinic instability process, while the nonlinear reverse kinetic energy cascade transfers the vortex kinetic energy to a larger scale and redistributes the vortex kinetic energy. And finally reach a statistical stable state. That is, the reverse kinetic energy cascade is a bridge between the characteristic scale of vorticity predicted by linear theory and the characteristic scale of vorticity observed in practice. Thirdly, by diagnosing the variation and anisotropy characteristics of reverse kinetic energy cascade with depth, the paper probes into the kinetic energy sink of reverse transfer. The preliminary results show that in the eastward strong current system of high vorticity kinetic energy, part of the reverse transfer kinetic energy is transmitted downward. At the same time, some of the kinetic energy transferred in the opposite direction is converted into the kinetic energy of the zonal mean flow. However, the contribution of the two energy sinks remains to be studied. Fourthly, the characteristics and mechanism of Interdecadal variation of mesoscale vortex field in the Kuroshio extension region are studied by using the method of reverse kinetic energy order series. The results show that baroclinic instability is not the control mechanism of Interdecadal oscillation of mesoscale vortex field in Kuroshio extensional body, and barotropic instability contributes positively to the Interdecadal oscillation of mesoscale vortex field. The nonlinear reverse kinetic energy cascade plays a decisive role in determining the spatial characteristics of mesoscale vortex field in the Kuroshio extensional body.
【学位授予单位】：中国科学院研究生院(海洋研究所)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P731.2

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