Interaction of Overflows and the Upper Ocean Circulation

深海充满了源自少数边缘海的密集水团。这些边缘海被狭窄的海峡和海槛部分地与开阔的海洋隔开，这可能导致边缘海形成特别密集的水团，以响应热损失或蒸发。当这些密集的水溢出海床时，就会从边缘海盆流出，由此产生的密集水流被称为“溢流”。溢流的动力学相当复杂，包括强烈的丢失和耗散，以及从几十公里到几十米的空间尺度。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，以及它们的能量特征。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水动力学的一个重要而有趣的元素，即溢水与上覆海洋之间的相互作用。在这项研究中，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流/上层海洋耦合的各个方面，将溢流置于活跃海洋的背景下。科学家团队将研究以下问题：海洋和溢流如何平衡夹带造成的质量损失/增加；斜压不稳定或其他非混合，主要是垂直相互作用产生的涡流对上层海洋有什么影响？溢出的位置重要吗？地形如何影响相互作用的结果？为了阐明溢出与上覆海洋耦合的动力学，研究人员将首先检查Jia（2000）的结果，将其作为主要动机，并将亚速尔海流作为这种相互作用的假定示例。然而，在现场，他们将使用一个相对简单的模型（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包括在溢流模型中还有待观察，但几乎可以肯定的是，他们将会发现，溢流对上层海洋有显著的影响，至少在溢流最剧烈运动和下降的局部地区是如此。这种影响是否像线状a羽那样是大规模的，还有待观察。更广泛的影响：溢流对气候动力学很重要，因为它们影响中深水域长期储存的特征。该项目不仅将参数化溢出（传统上，溢出对于gcm来说太小而无法解决），而且还将支持博士后在PI和co-PI的密切监督下执行所描述的计划。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渠道传播。

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.