Interaction of Overflows and the Upper Ocean Circulation

溢流与上层海洋环流的相互作用

• 批准号: 0424741
• 负责人: James Price
• 金额: --
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-08-01 至 2008-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0424741&HistoricalAwards=false
• 关键词: Interaction; Overflows; Upper; Ocean; Circulation

ABSTRACTOCE-0424741The deep ocean is filled with dense water masses that originate from a few marginal seas. These marginal seas are partially blocked from the open ocean by a narrow strait and a sill, which may cause a marginal sea to form an especially dense water mass in response to heat loss or evaporation. This dense water escapes from the marginal sea basin when it overflows the sill, and the resulting density currents have come to be called 'overflows'. The dynamics of overflows are of considerable complexity, including intense missing and dissipation and spatial scales from tens of kilometers to a few tens of meters. In the past five to ten years they have been an object of fairly intense study, owing principally to their well-documented importance for the thermohaline circulation, and too energetic features. However, most overflow studies have focused mainly upon the dynamics of the dense overflow currents in isolation from the overlying ocean, which is often assumed to be inactive. This may not be a valid assumption, or at minimum it may miss an important and interesting element of overflow dynamics, namely the interaction between the overflow and the overlying ocean. In this study, researchers from the Woods Hole Oceanographic Institution will put overflows into the context of an active ocean by studying aspects of the overflow/upper ocean coupling that must occur. The team of scientists will examine such questions as: how does the ocean and overflow balance the mass loss/gain caused by entrainment; what influence do the eddies created by baroclinic instability or other non-mixing, largely vertical interactions have within the upper ocean; does the location of the overflow matter; and how does topography affect the outcome of the interaction? To elucidate the dynamics that couple an overflow with the overlying ocean, the researchers will begin by examining the results of Jia (2000) as a primary motivation and the Azores Current as a putative example of this interaction. In the field however, they will carry out a process modeling study using a comparatively simple model (simple compared to a full OGCM). Whether they will find that the upper ocean has to be included in overflow models remains to be seen, but it is almost certain that they are going to find that overflows have a marked impact upon the upper ocean, as least locally in the region where overflows entrain and descend most vigorously. Whether this impact is large-scale, as occurs in the linear a-plume for example, also remains to be seen. Broader Impacts:Overflows are important for climate dynamics since they influence the characteristics of the long term storage at intermediate to deep waters. This project will not only parameterize overflows, which have traditionally have been too small for GCMs to resolve, but also support a post-doc who will carry out the described program under the close supervision of the PI and co-PI. The results from this research will be part of the PhD student's dissertation and disseminated through such venues as AGU-meetings and journal publications.

深海充满了来自少数边缘海的稠密水团。 这些边缘海被狭窄的海峡和岩床部分地与公海隔开，这可能导致边缘海在热损失或蒸发的反应中形成特别密集的水团。 当这些稠密的水溢出岩床时，就会从边缘海盆中逃逸出来，由此产生的异重流被称为“溢流”。 溢流的动力学是相当复杂的，包括强烈的失踪和耗散和空间尺度从几十公里到几十米。 在过去的五到十年里，它们一直是一个相当密集的研究对象，主要是由于它们对温盐环流的重要性以及过于活跃的特征。 然而，大多数溢流研究主要集中在与上覆海洋隔离的密集溢流流的动力学上，通常认为上覆海洋是不活跃的。 这可能不是一个有效的假设，或者至少它可能错过了溢流动力学的一个重要和有趣的元素，即溢流和上覆海洋之间的相互作用。 在这项研究中，来自伍兹霍尔海洋研究所的研究人员将通过研究溢出/上层海洋耦合的各个方面，将溢出置于活跃海洋的背景下。 科学家小组将研究这样的问题：海洋和溢流如何平衡卷吸造成的质量损失/增加;斜压不稳定或其他非混合，主要是垂直相互作用在上层海洋中产生的涡流有什么影响;溢流的位置是否重要;地形如何影响相互作用的结果？ 为了阐明溢流与上覆海洋耦合的动力学，研究人员将开始检查贾（2000）的结果作为主要动机，亚速尔群岛海流作为这种相互作用的假定例子。 然而，在现场，他们将使用相对简单的模型（与完整的OGCM相比简单）进行流程建模研究。 他们是否会发现上层海洋必须包括在溢流模型中还有待观察，但几乎可以肯定的是，他们会发现溢流对上层海洋有明显的影响，至少在溢流夹带和下降最有力的区域。 这种影响是否是大规模的，例如发生在线性a-羽流中，还有待观察。 更广泛的影响：溢流对气候动力学很重要，因为它们会影响中期至深层沃茨的长期储存特性。该项目不仅将解决传统上GCM无法解决的参数溢出问题，而且还将支持在PI和co-PI的密切监督下执行所述程序的博士后。 这项研究的结果将成为博士生论文的一部分，并通过AGU会议和期刊出版物等场所传播。