North Atlantic Oscillation contributes to the subpolar North Atlantic cooling in the past century
North Atlantic Oscillation contributes to the subpolar North Atlantic cooling in the past century
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DOI：
10.1007/s00382-023-06847-y
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发表时间：
2023-06
期刊：
影响因子：
4.6
通讯作者：
Yifei Fan;Wei Liu;Pengfei Zhang;Rui Chen;Laifang Li
中科院分区：
文献类型：
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作者：
Yifei Fan;Wei Liu;Pengfei Zhang;Rui Chen;Laifang Li
1900-2020年间，北大西洋副极地海域的海表温度（SST）以-0.39（）K/世纪的速率显著下降，这与全球变暖的趋势相反。亚极地北大西洋的冷却，即北大西洋冷团，可能是由涉及海洋和大气的许多机制驱动的。在这里，我们提出的证据表明，在北大西洋上空的大气环流的变化，特别是一个百年的趋势，朝着一个更积极的阶段，北大西洋涛动（NAO），可能有助于冷团。正NAO增强了副极地北大西洋的表面风，并导致海气界面的热量损失。根据理想化的混合层热平衡模式，NAO引起的热损失单独冷却副极地北大西洋0.26 K/世纪，这解释了67%的观测到的冷团SST趋势。NAO引起的冷却部分被东大西洋模式的变暖效应所抵消，大气环流变化的净效应解释了观测到的冷却趋势的44%。因此，除了海洋环流，包括大西洋经向翻转环流的减缓，大尺度大气环流可能发挥了同样重要的作用，促使百年来的SST变化的副极地北大西洋。
Sea surface temperature (SST) in the subpolar North Atlantic has significantly decreased at a rate of − 0.39 () K/century during 1900–2020, which runs counter to global warming due to anthropogenic forcing. The cooling in the subpolar North Atlantic, known as the North Atlantic cold blob, could be driven by a host of mechanisms involving both the ocean and atmosphere. Here, we present evidence that changes in the atmospheric circulation over the North Atlantic, in particular a centennial trend towards a more positive phase of the North Atlantic Oscillation (NAO), could have contributed to the cold blob. The positive NAO intensifies the surface wind over the subpolar North Atlantic and induces excessive heat loss from the air-sea interface. According to an idealized mixed layer heat balance model, the NAO induced heat loss alone cools the subpolar North Atlantic by 0.26 K/century, which explains 67% of the observed cold blob SST trend. The NAO-induced cooling is partially offset by the warming effect from the East Atlantic Pattern, and the net effect of changes in atmospheric circulation explains 44% of the observed cooling trend. Thus, besides ocean circulation, including the slowdown of the Atlantic Meridional Overturning Circulation, the large-scale atmospheric circulation might have played an equally important role in prompting the century-long SST changes in the subpolar North Atlantic.