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Quantifying the Effect of the Drake Passage Opening on the Eocene Ocean
Paleoceanography and Paleoclimatology ( IF 3.2 ) Pub Date : 2020-08-10 , DOI: 10.1029/2020pa003889
A. Toumoulin 1 , Y. Donnadieu 1 , J.‐B. Ladant 2 , S. J. Batenburg 3 , F. Poblete 4 , G. Dupont‐Nivet 3, 4, 5
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The opening of the Drake Passage (DP) during the Cenozoic is a tectonic event of paramount importance for the development of modern ocean characteristics. Notably, it has been suggested that it exerts a primary role in the onset of the Antarctic Circumpolar Current (ACC) formation, in the cooling of high‐latitude South Atlantic waters and in the initiation of North Atlantic Deep Water (NADW) formation. Several model studies have aimed to assess the impacts of DP opening on climate, but most of them focused on surface climate, and only few used realistic Eocene boundary conditions. Here, we revisit the impact of the DP opening on ocean circulation with the IPSL‐CM5A2 Earth System Model. Using appropriate middle Eocene (40 Ma) boundary conditions, we perform and analyze simulations with different depths of the DP (0, 100, 1,000, and 2,500 m) and compare results to existing geochemical data. Our experiments show that DP opening has a strong effect on Eocene ocean structure and dynamics even for shallow depths. The DP opening notably allows the formation of a proto‐ACC and induces deep ocean cooling of 1.5°C to 2.5°C in most of the Southern Hemisphere. There is no NADW formation in our simulations regardless of the depth of the DP, suggesting that the DP on its own is not a primary control of deepwater formation in the North Atlantic. This study elucidates how and to what extent the opening of the DP contributed to the establishment of the modern global thermohaline circulation.

中文翻译:

量化幼龙通道开口对始新世的影响

新生代德雷克海峡(DP)的开放是对现代海洋特征发展至关重要的构造事件。值得注意的是,有人认为它在南极绕极洋流(ACC)的形成,高纬度南大西洋水域的冷却以及北大西洋深水(NADW)的形成中起主要作用。数个模型研究旨在评估DP开口对气候的影响,但大多数研究集中在地表气候,只有极少数使用了现实的始新世边界条件。在这里,我们使用IPSL-CM5A2地球系统模型来回顾DP开口对海洋环流的影响。使用适当的始新世中期(40 Ma)边界条件,我们执行并分析了不同深度的DP(0、100、1,000和2,500 m),并将结果与​​现有地球化学数据进行比较。我们的实验表明,DP开口对始新世海洋结构和动力学都具有很强的影响,即使在浅深度也是如此。DP开口明显允许形成原ACC,并在南半球的大部分地区引起1.5°C至2.5°C的深海冷却。无论DP的深度如何,我们的模拟中都没有NADW的形成,这表明DP本身并不是北大西洋深水形成的主要控制因素。这项研究阐明了DP的开放如何以及在多大程度上促成了现代全球热盐循环的建立。DP开口明显允许形成原ACC,并在南半球的大部分地区引起1.5°C至2.5°C的深海冷却。无论DP的深度如何,我们的模拟中都没有NADW的形成,这表明DP本身并不是北大西洋深水形成的主要控制因素。这项研究阐明了DP的开放如何以及在何种程度上有助于建立现代全球热盐循环系统。DP开口明显允许形成原ACC,并在南半球的大部分地区引起1.5°C至2.5°C的深海冷却。无论DP的深度如何,我们的模拟中都没有NADW的形成,这表明DP本身并不是北大西洋深水形成的主要控制因素。这项研究阐明了DP的开放如何以及在多大程度上促成了现代全球热盐循环的建立。
更新日期:2020-08-10
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