Transport by Intrusions Generated by Boundary Mixing

边界混合产生的侵入传输

• 批准号: 0647253
• 负责人: Chris Rehmann
• 金额: --
• 依托单位: Iowa State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-03-15 至 2011-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0647253&HistoricalAwards=false
• 关键词: Transport; Intrusions; Generated; Boundary; Mixing

OCE-0647253Field observations over the last decade suggest that mixing near basin boundaries exceeds that in the interior by an order of magnitude or more and largely determines the basin-averaged mixing rate. In the ocean, boundary mixing has been attributed to critical reflection of internal waves on topography and internal waves generated by internal tides flowing over rough topography. In lakes, boundary mixing is due to critical reflection and turbulence generated by bottom currents from seiches. Although much recent work has focused on boundary mixing processes, there has been little work on the ultimate fate of the mixed fluid. In this study, field experiments will be conducted to determine how fluid mixed at the boundary of a stratifiedwater body is transported to the interior. Experiments will be conducted in two lakes in Iowa: Ada Hayden Lake, near Iowa State University and West Okoboji Lake, which is larger and deeper. The objectives of the proposed work are to 1) classify the response of lakes to forcing according to the properties of the resulting internal wave field and mean currents, 2) identify intrusions and relate the turbulence and mixing to the forcing, and 3) to track the intrusions as they evolve. The lakes differ in size and one hypothesis that will be tested is that the magnitudes of potential energy change and energy supplied for mixing depend on the size of the lake but the ratio of these rates (called the mixing efficiency) will be larger on the sloping sides of the lake than along the flat bottom. Measurements of currents and temperature will be made and the spectra of internal waves will be calculated. Intrusions will be tracked with a fluorescent dye and microstructure measurements will be made throughout the dye patch.Broader impacts of the proposed work include the training of graduate and undergraduatestudents, outreach to a rural school near Iowa State University, and outreach based out of the Iowa Lakeside Laboratory. This will a new summer class on physical limnology at the Lakeside Laboratory as well as non-credit courses for local residents and K-12 schools. Graduate students in the PI's research group will both conduct the experiments for the proposed research and participate in the outreach activities. Requested equipment will enhance the infrastructure for research. The PI's research group has broadened participation of underrepresented groups and disseminated results to the public through its past activities. Results from this project will affect and connect oceanography, limnology, and engineering; in particular, the outreach will increase awareness of local and national water quality issues.

在过去的十年中，OCE-0647253的观测表明，在盆地接近边界的混合超过了内部的数量级或更多的内部，并且很大程度上决定了盆地平均混合率。在海洋中，边界混合归因于内部波的临界反射在地形和内部波浪中，由内部潮汐在粗糙的地形上流动。在湖泊中，边界混合是由于seiches底电流产生的临界反射和湍流所致。尽管最近的许多工作集中在边界混合过程上，但在混合流体的最终命运上几乎没有工作。 在这项研究中，将进行现场实验，以确定如何将分层水体边界的流体转运到内部。实验将在爱荷华州的两个湖泊中进行：爱荷华州立大学附近的艾达·海登湖（Ada Hayden Lake）和西奥科博吉湖（West Okoboji Lake），湖更大，更深。提议的工作的目标是1）根据所得内波场和平均电流的特性对湖泊对强迫的响应进行分类，2）确定侵入并将湍流和混合与强迫相关，以及3）以跟踪侵入的进化。湖泊的大小不同，将要检验的一个假设是，用于混合的势能变化和能量的幅度取决于湖泊的大小，但是这些速率的比率（称为混合效率）在湖面的倾斜侧将比沿平坦的底部更大。将进行电流和温度的测量，并将计算内波的光谱。将在整个染料斑块中进行荧光染料的入侵，并将进行微观结构测量。拟议工作的Boader影响包括培训研究生和本科生的培训，对爱荷华州立大学附近的乡村学校的外展，以及基于爱荷华州拉西赛德（Iowa Lakeside Lakeside Lakeside Lakeside Lakeside）实验室的外展活动。这将是湖边实验室的物理林木学的新夏季课，以及当地居民和K-12学校的非学分课程。 PI研究小组的研究生将对拟议的研究进行实验，并参与外展活动。请求的设备将增强研究基础设施。 PI的研究小组扩大了代表性不足的小组的参与，并通过其过去的活动向公众传播了结果。该项目的结果将影响并连接海洋学，羊水学和工程；特别是，宣传将提高人们对地方和国家水质问题的认识。