Collaborative Research: Formation of Multiple Zonal Jets in the Oceans

最近的观测和模拟研究表明，海洋包含多个交替的近带状喷流，覆盖所有海洋盆地，并从海洋顶部渗透到底部。急流的典型宽度为100-300 km，典型速度为1-5 cm/s，急流嵌入大尺度洋流中。海洋喷流也可能与木星等巨型气体行星大气中的多股交替喷流在动力学上有关。大气射流已经研究了几十年，大气界发展了一套有用的理论思想。在这些理论中占主导地位的假设是，这些射流是一种非线性现象，由涡流维持。然而，不仅大气射流仍然知之甚少，而且相应的理论思想与海洋射流的相关性也受到质疑。多重喷流形成的潜在机制将与海洋环流模式的层次进行研究。其中心思想是理解能够维持所观察到的射流并确定其结构的物理机制。具体目标是：（i）在现有观测的背景下系统地描述喷流的现象学;（ii）建立喷流特性对各种物理因素的依赖关系;（iii）分析喷流内涡流通量收敛和各向异性混合的重要性;（iv）检查与喷流相关的低频变化;（v）确定喷流形成的机制。基本的流动机制和射流特性将通过分析非线性解和流动分量的线性稳定性分析来研究。需要解释的重要属性包括垂直和垂直结构，振幅和射流的瞬态变化。将连接到现有的大气射流的想法，以及各向异性湍流更广泛的文献。这个项目将解决基本的，但了解甚少的物理学这一类特殊的海洋涡流/大尺度相互作用，使用理论，模型和观测。这项工作必须为多喷流的新兴观测提供物理基础。与这些射流相关的高度各向异性运输的参数化是另一个研究课题，将受益于对这种现象的基本理解。该项目将支持迈阿密大学的一名研究生。

Observational and modeling studies have recently demonstrated that the ocean contains multiple, alternating, nearly zonal jets that cover all oceanic basins and penetrate from the top to the bottom of the ocean. The typical width of each jet is 100-300 km, typical velocity is 1-5 cm/s, and the jets are embedded in the large-scale oceanic currents. The oceanic jets may be also dynamically related to the multiple alternating jets in the atmosphere of such giant gas planets as Jupiter. The atmospheric jets have been studied for a few decades, and the atmospheric community developed a set of useful theoretical ideas. The prevailing hypothesis in these theories is that these jets are a nonlinear phenomenon, maintained by eddies. However, not only do the atmospheric jets remain poorly understood, but also the relevance of the corresponding theoretical ideas to the oceanic jets is under question. Potential mechanisms of the multiple jet formation will be studied with a hierarchy of ocean circulation models. The central idea is to understand physical mechanisms that can maintain the observed jets and determine their structure. Specific objectives are to: (i) systematically describe phenomenology of the jets in the context of available observations; (ii) establish dependence of jet properties on various physical factors; (iii) analyze importance of eddy flux convergences and anisotropic mixing within the jets; (iv) examine low-frequency variability associated with the jets, and (v) determine the mechanisms of jet formation. The underlying flow mechanisms and jet properties will be studied both with analysis of the nonlinear solutions and with linear stability analysis of the flow components. Important properties that need to be explained include meridional and vertical structures, amplitude, and transient variability of the jets. Connection will be made to existing atmospheric-jet ideas, as well as to the broader literature on anisotropic turbulence. This project will address fundamental but poorly understood physics of this particular class of oceanic eddy/large-scale interactions, using theory, models, and observations. The work has to do with providing the physical basis for the emerging observations of the multiple jets. Parameterization of highly anisotropic transport associated with these jets is another research topic that will benefit from fundamental understanding of the phenomenon. This project will support one graduate student at the University of Miami.