Numerical Investigations of Currents, Eddy Kinetic Energy, and Internal-waves in the Southern Ocean

摘要：南大洋（SO）的深海混合在控制全球翻转环流中起着至关重要的作用，这种环流将热量、淡水和溶解的温室气体重新分配到世界海洋中。水团输入、转化和输出到世界其他地方的速率是由南大洋经向翻转环流和几个内部动力学控制的。然而，太平洋环流是纬向无界流的唯一海洋实例，因此不受斯维德鲁普动力学的影响。相反，热、淡水、溶解气体和营养物质的所有经向输送都是通过经向流动完成的。以前的许多ACC动力学模型都假定所有的水改变都发生在地表，而下面的地表水沿着等平面向北或向南流动。然而，最近在南大洋进行的一系列研究表明，传播内波的非绝热通量太大，不容忽视。在这项研究中，加州大学圣地亚哥分校斯克里普斯海洋学研究所的一名研究人员将通过一系列理想化的数值实验，研究在纬向无界流（如ACC）中，高能内波在净经向环流中的相对重要性。实验将在实际的平均纬向流和地转涡旋场上施加一个与各种波产生模型相一致的内波向上传播场。根据先前和初步的工作，由于固有的非线性动力学，吸收到临界层以及与涡涡性的相互作用，波浪将会破裂。内波传播的能量损失率将决定破波的垂直结构以及相关的经向应力和水质量变化的深度。更广泛的影响：这项工作的结果不仅将导致对南大洋经向翻转环流的更好理解，而且还将提高社区的概念理解和业务气候模式的准确性。南大洋环流通过调节全球运动和热量、淡水、溶解的温室气体和生物必需营养物质的储存，在地球气候中起着极其重要的作用。目前的全球尺度模式可能由于没有适当地包括南大洋动力学中破碎内波的绝热强迫而受到影响。为了准确地理解和模拟过去、现在和未来气候的大尺度环流，需要对混合的地理结果有一个动态的了解。该项目的直接目标是发展一种动态理解，使这些影响能够适当地参数化，以提高我们的概念理解和业务气候模型的准确性。

ABSTRACTOCE-0525758Intellectual Merit:Diapyncal mixing in the Southern Ocean (SO) plays a vital role in controlling the global over- turning circulation that redistributes heat, freshwater, and dissolved greenhouse gases throughout the world's oceans. The rate at which water masses are imported, transformed, and exported to the rest of the world are controlled by the Southern Ocean Meridional Overturning Circulation and several interior dynamics. However, the ACC represents the only oceanic instance of a zonally unbounded flow, and is therefore not subject to Sverdrup dynamics. Instead, all meridional transport of heat, freshwater, dissolved gases, and nutrients is accomplished through meridional flows. Many previous models of ACC dynamics have assumed that all water modification has occured at the surface while the surface water below has flowed northward or southward along isopycnal surfaces. However, a series of recent studies in the Southern Ocean has suggested that the diabatic fluxes from propagating internal-waves are too large to be ignored. In this study, a researcher at the University of California-San Diego Scripps Institution of Oceanography will investigate the relative importance of breaking energetic internal waves on the net meridional circulation in a zonally unbounded flow such as the ACC through a series of idealized numerical experiments. The experiments will impose an upward propagating field of internal waves, consistent with various models of wave generation, onto a realistic mean zonal flow and geostrophic eddy field. Based on previous and preliminary work, the waves will break due to a combination of intrinsic nonlinear dynamics, absorption into critical layers, and interaction with eddy vorticity. The rate of energy loss from propagating internal waves will determine the vertical structure of wave-breaking and the depth of associated meridional stresses and water mass modification. Broader Impacts:The results from this work will not only lead to a better understanding of the Meridional Overturning Circulation of the Southern Ocean but also improve the communities conceptual understanding and the accuracy of operational climate models. The circulation of the Southern Ocean plays an extremely important role in the earth's climate by regulating the global movement and storage of heat, freshwater, dissolved greenhouse gases, and biologically essential nutrients. Current global scale models may suffer from not appropriately including the diabatic forcing from breaking internal-waves in Southern Ocean dynamics. A dynamical understanding of the resultant geography of mixing is required for accurate understanding and modeling of the large-scale circulation in past, present and future climates. The immediate goal of this project is to develop a dynamical understanding that will allow appropriate parameterization of these effects to improve our conceptual understanding and the accuracy of operational climate models.