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.

OCE-0647253过去十年的现场观测表明，盆地边界附近的混合超过内部一个数量级或更多，并在很大程度上决定了盆地平均混合速率。在海洋中，边界混合被归因于内波在地形上的临界反射和内潮流过粗糙地形产生的内波。在湖泊中，边界混合是由于临界反射和湍流所产生的底流从假潮。虽然最近的工作主要集中在边界混合过程中，一直很少有工作的混合流体的最终命运。 在这项研究中，将进行现场实验，以确定流体混合在边界的分层水体是如何输运到内部。实验将在爱荷华州的两个湖泊进行：靠近爱荷华州州立大学的阿达海登湖和更大更深的西奥科博吉湖。拟议工作的目标是：1）根据所得的内波场和平均流的特性对湖泊对强迫的响应进行分类，2）识别入侵并将湍流和混合与强迫联系起来，3）跟踪入侵的演变。湖泊的大小不同，一个将被检验的假设是，势能变化的大小和为混合提供的能量取决于湖泊的大小，但是这些速率的比率（称为混合效率）在湖的倾斜侧上将大于沿着平坦的底部。将进行电流和温度的测量，并计算内波的频谱。将用荧光染料跟踪侵入物，并在整个染料斑中进行微观结构测量。拟议工作的更广泛影响包括研究生和本科生的培训，对爱荷华州州立大学附近农村学校的推广，以及基于爱荷华州湖畔实验室的推广。这将是一个新的夏季班的物理湖沼学在湖滨实验室，以及非学分课程，为当地居民和K-12学校。PI研究小组的研究生将为拟议的研究进行实验，并参加外展活动。所要求的设备将加强研究基础设施。国际和平研究所的研究小组扩大了代表性不足群体的参与，并通过其以往的活动向公众传播了研究结果。该项目的成果将影响和连接海洋学，湖沼学和工程学;特别是，推广活动将提高对地方和国家水质问题的认识。