Equatorial Macro Turbulence: Extending Mid-Latitude Macro Turbulence Studies to the Equatorial Region

在中纬度地区，大尺度湍流海洋环流通常演变为大尺度喷流和涡旋的模式，称为地转湍流。虽然地转乱流的理论已经研究了几十年，但它只是最近才被观测到，这些观测表明它在整个外热带海洋中普遍存在。在赤道海洋中进行的类似观察，促使这位科学家考虑如何在赤道海洋中修改地转湍流理论，因为在赤道海洋中，科里奥利参数的相对变化很大，地转不起作用。在这项研究中，他将运用理论和数值模型的层次来发展赤道地区宏观湍流的图景，这将补充现有的地转湍流理论。正在考虑的理论的一个方面被称为莱茵效应：由于罗斯比波和湍流的相互作用，交替的纬向射流形成。发生这种情况的长度尺度在赤道附近比在中纬度地区变化得更快，因此动力学更为复杂。能量级联也在考虑之中。在简单的单层地转湍流中，能量和熵的同时守恒导致运动向更大的尺度演化。当考虑到科里奥利参数的相对快速变化时，那么能量不仅必须向更高的长度尺度级联，而且必须向更大的变形半径级联，从而向赤道级联。除了这项工作的智力价值外，该项目还将支持一个创新的试点项目，由一名美国物理海洋学研究生在肯尼亚呆三个月，以促进工业化国家和发展中国家之间的科学合作。这一试点方案将与政府间海洋学委员会协调进行。

In the mid-latitudes, the large-scale turbulent ocean circulation commonly evolves towards a pattern of large-scale jets and vortices, which is known as geostrophic turbulence. While the theory of geostrophic turbulence has been studied for decades, it has only been observed relatively recently and those observations suggest that it is ubiquitous throughout the extratopical ocean. Similar observations made in the equatorial ocean, prompted this scientist to consider how the theory of geostrophic turbulence must be modified in the equatorial ocean where the relative change in the Coriolis parameter is large and geostrophy fails. In this study, he will employ theory and a hierarchy of numerical models to develop a picture of macro turbulence in the equatorial region which will complement existing theories of geostrophic turbulence. One aspect of the theory that is being considered is known as the Rhines effect: alternating zonal jets form due to the interaction of Rossby waves and the turbulence. The length scale at which this happens varies near the equator more rapidly than in mid-latitudes and hence the dynamics are more complex. The cascade of energy is also being considered. In simple one-layer geostrophic turbulence, the concurrent conservation of energy and enstrophy causes motions to evolve towards larger scales. When the relatively rapid change in the Coriolis parameter is considered, then energy must not only cascade towards higher length scales but also towards larger deformation radii and hence towards the equator. In addition to the intellectual merit of this work, this project will support an innovative pilot program where a U.S. graduate student in physical oceanography will spend three months in Kenya to facilitate scientific collaborations between the industrialized and developing world. This pilot program will be done in coordination with the Intergovernmental Oceanographic Commission.