Investigating the Role of the Tibetan Plateau in the Formation of Atlantic Meridional Overturning Circulation
Investigating the Role of the Tibetan Plateau in the Formation of Atlantic Meridional Overturning Circulation
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DOI：
10.1175/jcli-d-19-0205.1
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发表时间：
2020-03
影响因子：
4.9
通讯作者：
Haijun Yang;Qingnong Wen
中科院分区：
文献类型：
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作者：
Haijun Yang;Qingnong Wen
青藏高原对区域和全球气候都有重要影响。它甚至可以影响遥远的大西洋纬向翻转环流（AMOC），如本研究所示。通过耦合模拟实验，我们证明，去除TP立即减弱东亚上空的纬向风，导致更强的西风在中纬度地区。较强的西风增强了向南的Ekman流和表面潜热和感热损失在副极地北大西洋，冷却表面海洋，并导致更强的北大西洋深水形成和更强的AMOC在TP去除后的头几十年。与此同时，随着热带太平洋信风减弱，更多的水分从热带太平洋输送到北大西洋，使表层海洋清新，并引发AMOC减弱。AMOC的减弱反过来又导致海冰向南扩张和融化，为北大西洋提供更多的淡水，这进一步削弱了AMOC。AMOC和海冰之间的正反馈最终导致AMOC关闭。我们说明，没有TP就不会有AMOC。这些结果要求重新审视海洋环流和全球气候可能对TP隆起和地质时间尺度上的其他构造变化做出的反应。
The Tibetan Plateau (TP) over the Eurasian continent has significant effects on both regional and global climate. It can even affect the remote Atlantic meridional overturning circulation (AMOC), as shown in this study. Through coupled modeling experiments, we demonstrate that removing the TP immediately weakens the meridional wind over East Asia, resulting in stronger westerlies in the midlatitudes. The stronger westerlies enhance the southward Ekman flow and surface latent and sensible heat losses in the subpolar North Atlantic, cooling the surface ocean and leading to stronger North Atlantic deep-water formation and stronger AMOC during the first few decades after the TP removal. At the same time, accompanying the weakened trade winds in the tropical Pacific, more moisture is transported from the tropical Pacific to the North Atlantic, freshening the surface ocean and triggering a weakening of the AMOC. The AMOC weakening in turn results in southward expansion and melting of sea ice, providing more freshwater to the North Atlantic, which furthers the weakening of the AMOC. The positive feedback between the AMOC and sea ice eventually leads to AMOC shutdown. We illustrate that there would be no AMOC without the TP. These results call for a revisiting of how ocean circulation and global climate may have responded to the TP uplift and other tectonic changes on the geological time scale.