Interaction of Overflows and the Upper Ocean Circulation

深海充满了来自少数边缘海的致密水团。这些边缘海被狭窄的海峡和基岩部分地与公海隔绝，这可能会导致边缘海因热量损失或蒸发而形成特别稠密的水团。当这些稠密的水溢出海床时，它们就会从边缘海盆中逸出，由此产生的致密流就被称为“溢流”。溢流的动力学相当复杂，包括剧烈的失踪和消散，空间尺度从几十公里到几十米。在过去的五到十年里，它们一直是相当密集的研究对象，主要是因为它们对温盐循环的重要性已经得到了充分的证明，而且它们的能量太高了。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的动力学上，而上覆海洋通常被认为是不活跃的。这可能不是一个有效的假设，或者至少它可能遗漏了溢出动力学中一个重要而有趣的元素，即溢出与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必须发生的溢出/上层海洋耦合的各个方面，将溢出置于活跃海洋的背景下。科学家团队将研究这样的问题：海洋和溢流如何平衡卷吸造成的质量损失/收益；斜压不稳定或其他非混合、主要是垂直的相互作用产生的涡流在上层海洋中有什么影响；溢流的位置重要吗；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，研究人员将首先检验贾(2000)的结果作为这种相互作用的主要动机，并将亚速尔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)进行过程建模研究。他们是否会发现上层海洋必须被包括在溢出模型中还有待观察，但几乎可以肯定的是，他们将发现溢出对上层海洋有显著的影响，至少在溢出卷曲和下降最剧烈的地区是如此。这种影响是否像发生在线性a-烟柱中的那样是大范围的，也有待观察。更广泛的影响：溢流对气候动态很重要，因为它们影响到中至深水的长期储存特征。该项目不仅将传统上难以解决的溢出问题参数化，而且还将支持一名博士后，他将在PI和共同PI的密切监督下执行所述计划。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。

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.