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

合作研究：地中海流出水对北大西洋气候变化的影响

• 批准号: 0630229
• 负责人: Eric Chassignet
• 金额: $ 82.44万
• 依托单位: Florida State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-01 至 2010-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0630229&HistoricalAwards=false
• 关键词: Collaborative; Research; Influence; Mediterranean; Outflow

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.

地中海对流产生温暖的咸水团，流经直布罗陀海峡，在中深处流入大西洋，形成全球海洋中最明显的属性分布舌之一。这些溢流水对北大西洋盆地的动力和性质的影响与其相对较小的体积通量不成比例。高盐度直接或间接地通过平流或混合作用为北欧海表层海水的深层对流提供了条件。此外，这些水在北大西洋东部建立了一个深度范围大大超过溢流厚度的属性场，并影响了整个中深度亚热带盆地，影响了东部盆地的动力学。地中海人口流动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，温度和盐度有所增加。本研究的两个主要问题是：这些变化的时空背景是什么？这些变化对北大西洋东部和整个盆地的属性场和动力学有什么影响？为了解决这些问题，提出了数据和模型分析，不仅评估地中海溢流变率对流域的影响，而且还评估其他变率来源的相对重要性。虽然过去的研究主要集中在地中海造成的中尺度变化上，但我们的重点将放在年际和年代际时间尺度上。总体而言，地中海溢流水的盐化与观测到的高纬度地表水和北大西洋北部对流水团的变新鲜形成鲜明对比。如果高纬度水域继续变新鲜，向深海输送热量的大部分对流活动可能会落在中纬度地区的源水域，这为地中海溢流水域的研究提供了额外的动力。学术价值：这项工作将确定对北大西洋东部和全球海洋气候的特性起重要作用的水团长期变化的来源。此外，还将评估流域对时变溢流的动态响应，以建立流域属性场的时空变异性。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如何通过开放海洋传播，并将有助于改进整个全球海洋溢流水域的建模。最后，这项工作将培养研究生的建模和数据分析能力。