Abstract The Mediterranean overflow water is one of the most important intermediate-depth water masses in the North Atlantic. To investigate its properties a pre-industrial simulation with the earth system model EC-Earth is used. The multidecadal variability of the outflow is analysed by examining the modelled volume and salt transports through the Strait of Gibraltar as well as different atmospheric patterns (such as the wind pattern and the net freshwater fluxes). The salinity evolution in the main core of the outflow in the mid-Atlantic is also taken into account. The leading empirical orthogonal functions for the modelled salinity 900 m coincided with the modelled distribution of outflow water. The associated principal component showed a multidecadal variability of the salinity field. The variability of the net salt transport through the Strait of Gibraltar showed a similar behaviour where the Atlantic-Mediterranean system manifested two clear states. One of these is when the Mediterranean imports salt from the Atlantic and the other is where salt export to the Atlantic predominates. This result indicates that the Mediterranean Sea acts as a storage of salt alternating between the two states. The negative phase of the North Atlantic oscillation appears to play a role driving the variability of the salt transport and its impact on the overturning circulation in the North Atlantic.

中文翻译：

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北大西洋地中海溢流水及其多年变化

摘要 地中海溢流水是北大西洋最重要的中深水团之一。为了研究其特性，使用了地球系统模型 EC-Earth 的工业化前模拟。通过检查模拟的体积和通过直布罗陀海峡的盐分输送以及不同的大气模式（例如风模式和净淡水通量）来分析流出量的数十年变化。大西洋中部流出的主要核心的盐度演变也被考虑在内。模拟盐度 900 m 的主要经验正交函数与模拟出水分布一致。相关的主成分显示了盐度场的数十年变化。通过直布罗陀海峡的净盐运输的变化表现出类似的行为，其中大西洋 - 地中海系统表现出两种清晰的状态。其中之一是地中海从大西洋进口盐，另一个是向大西洋出口的盐占主导地位。这一结果表明，地中海充当了两个国家之间交替的盐库。北大西洋振荡的负相位似乎在驱动盐输运的变异性及其对北大西洋翻转环流的影响中发挥作用。这一结果表明，地中海充当了两个国家之间交替的盐库。北大西洋振荡的负相位似乎在驱动盐输运的变异性及其对北大西洋翻转环流的影响中发挥作用。这一结果表明，地中海充当了两个国家之间交替的盐库。北大西洋振荡的负相位似乎在驱动盐输运的变异性及其对北大西洋翻转环流的影响中发挥作用。