Collaborative Research: The Influence of the Mediterranean Outflow Water on the Climatic Variability of the North Atlantic

-0452679/0452706地中海对流产生了一个温暖的咸水团，从直布罗陀海床流入大西洋的中部，形成了全球海洋中最显著的性质分布舌头之一。这些溢流水对北大西洋盆地的动力学和性质的影响与其相对较小的体积通量不成比例。高盐度有助于北欧海域表层水直接通过平流或通过混合间接地对深对流进行预调节。此外，这些水域在北大西洋东部建立了属性场，其深度范围大大超过了溢流厚度，并影响了整个中深度亚热带盆地的动态。地中海溢出赌注的可变性在很大程度上被忽视了。最近的一项研究表明，在过去的50年里，温度和盐度都在上升。这项研究的两个主要问题是：这些变化的时空背景是什么，以及这些变化对北大西洋东部的物性场和动力学以及整个盆地的影响是什么？为解决这些问题，建议进行数据和模拟分析，以便不仅评估地中海溢流变化对盆地的影响，而且评估其他变化来源的相对重要性。虽然过去的研究侧重于冰川造成的中尺度变异性，但我们的重点将是总体上的年际和年代际时间尺度，地中海溢流水的盐碱化与观察到的高纬度地表水域和来自北大西洋北部的对流水团的淡化形成鲜明对比。如果高纬度水域继续变淡，大部分向深海输送热量的对流活动可能会落到中纬度的源头水域，为地中海溢出水域的研究提供额外的动力。学术价值：这项工作将确定对北大西洋东部的性质和全球海洋气候起重要作用的水团的长期变异性的来源。此外，还将评估盆地对时间变化的溢出的动态响应，以确定盆地属性场的空间和时间变异性。更广泛的影响：对溢流命运的更好理解将阐明边缘海的变化是如何通过开阔海洋传播的，并将有助于改进对整个全球海洋的溢流水域的建模。最后，这项工作将培训一名研究生建模和数据分析。

ABSTRACTOCE-0452679/0452706Convection in the Mediterranean Sea produces a warm salty water mass that flows over the Gibraltar sill into the Atlantic at mid-depth, forming one of the most pronounced property distributions tongue in the global ocean. The impact of these overflow waters on the dynamics and properties of the North Atlantic basin is disproportionate to its relatively small volume flux. The high salinity contributes to the preconditioning of the surface waters in the Nordic Seas for deep convection, either directly via advection or indirectly via mixing. Additionally, these waters establish the property fields in the eastern North Atlantic over a depth range that considerably exceeds the overflow thickness, and of the entire mid-depth subtropical basin, influence the dynamics of the eastern basin. The variability of the Mediterranean overflow wagters has been largely ignored. A recent study has shown increases in the temperature and salinity over the past fifty years. The two main questions of this study are: what is the spatial and temporal context for these changes, and what is the impact of these changes on the property fields and dynamics of the eastern North Atlantic and on the basin as a whole? To address these questions, data and modeling analyses are proposed to assess not only the consequence of Mediterranean overflow variability on the basin, but also the relative importance of other sources of variability. While past studies have focused on the mesoscale variability created by Meddies, our focus will be on interannual and decadal time scales Overall, the salinification of the Mediterranean overflow waters stands in sharp contrast to the observed freshening of high latitude surface waters and of the convective water masses emanating from the northern North Atlantic. If high latitude waters continue to freshen, the bulk of the convective activity that sends heat to the deep ocean may fall to source waters at mid-latitudes, providing added impetus for the study of the Mediterranean overflow waters. Intellectual Merit: This work will determine the source of long-term variability for a water mass that plays an important role for the properties of the eastern North Atlantic, and for the climate of the global ocean. Additionally, the dynamic response of a basin to a temporally varying overflow will be evaluated to establish the spatial and temporal variability of the basin's property fields. Broader Impacts: An improved understanding of the fate of the overflow will illuminate how changes in a marginal sea are transmitted through the open ocean, and will help improive the modeling of overflow waters throughout the global ocean. Finally, this work will train a graduate student in modeling and data analyses.