Collaborative Research: Internal Lee-Wave Dissipation in Oceanic Flows with Mean Shear

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项目编号	1756093
	Collaborative Research: Internal Lee-Wave Dissipation in Oceanic Flows with Mean Shear
	Eric Kunze
主持机构	NorthWest Research Associates, Incorporated
项目开始年	2018
	2018-09-15
项目结束日期	2022-08-31
资助机构	US-NSF
项目类别	Standard Grant
项目经费	245996(USD)
国家	美国
语种	英语
英文摘要	The mechanisms for dissipating the ocean's balanced flow remain uncertain but are important for correctly simulating oceanic circulation. Dissipation through internal lee-wave generation followed by turbulence production has been proposed to account for 20-75% of the needed loss. However, microstructure measurements do not agree with the predicted dissipation. This research will explain this discrepancy and better constrain the role of lee-waves in dissipating vs. redistributing energy. This study will carry out numerical simulations describing the generation, propagation, dissipation, and reabsorption of internal lee-waves in areas where earth rotation-induced flows of finite extent are dominant. Results from this project will be presented at conferences and published in peer-reviewed journals to make them available to the wider scientific community. The results of this study will provide an improved parameterization for the dissipation and redistribution of balanced flows and induced mixing by lee-wave generation and increase the accuracy of Ocean circulation modeling. The project will support education and mentoring of a graduate student in numerical modeling and internal-wave physics, and an undergraduate student in research. The research will also be utilized in outreach activities for the general public and K-12 science teachers, as well as undergraduate and international student training. Large amounts of power, equivalent of 1 TW, is thought to be input into the ocean circulation by wind-work. The maintenance of steady state conditions (i.e., constant energy levels) in the world's oceans requires that addition of energy by the wind is balanced through energy dissipation processes. Internal lee-wave generation has been assumed to be one of the largest predicted energy sinks dissipating 0.2 to 0.75 TW through turbulence generation. However, measurements in Antarctic Circumpolar Current jets find that turbulent dissipation rates fall short of predictions by as much as an order of magnitude. Recent numerical simulations of spontaneous near-inertial wave generation in the Kuroshio Front find that much of the generated wave energy is reabsorbed back into the mean flow. If reabsorption also occurs for lee waves, they would be as much a mechanism for redistributing balanced energy as dissipating it. These numerical simulations will determine what fractions of lee-wave energy are lost to turbulence vs. being reabsorbed into the mean flow and hence address whether lee-wave generation represents a major sink for the large-scale circulation. Missing key elements have been sheared flow and wave action (E/w) conservation where E is the wave energy density, w = kU the Lagrangian frequency of the lee wave, k the topographic wavenumber and U the flow speed. In a bottom-intensified rotating shear flow, the fraction kU1/(kUo) is available for dissipation and (kUo- kU1)/(kUo) for reabsorption, where Uo is the bottom flow speed and U1 > f/k the flow where the waves break. The numerical simulations will test realistic ocean flow and topography configurations to determine whether reabsorption is a significant fraction of lee-wave generation in the ocean. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/73446
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Eric Kunze.Collaborative Research: Internal Lee-Wave Dissipation in Oceanic Flows with Mean Shear.2018.