Decreasing intensity of open-ocean convection in the Greenland and Iceland seas
Decreasing intensity of open-ocean convection in the Greenland and Iceland seas
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DOI：
10.1038/nclimate2688
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发表时间：
2015-09-01
影响因子：
30.7
通讯作者：
Renfrew, I. A.
中科院分区：
文献类型：
--
作者：
Moore, G. W. K.;Vage, K.;Renfrew, I. A.
热量和淡水的海气交换在全球气候系统中起着至关重要的作用(1)。格陵兰海和冰岛海尤其如此，在那里，这些通量驱动海洋对流，形成丹麦海峡溢水，这是大西洋经向翻转环流（AMOC；参考文献2）下肢最密集的组成部分。这里我们表明，该地区冬季海冰的退缩，加上格陵兰海和冰岛海的大气和海面变暖的不同速率，导致自1979年以来冬季海气热通量的幅度在统计上显著减少了约20%。我们还表明，除了北大西洋涛动（NAO，参考文献3-7）之外，还需要其他气候变率模态来充分表征区域海气相互作用。混合层模式模拟表明，大气强迫的进一步减弱将超过格陵兰海的一个阈值，因此对流将受到深度限制，减少北欧海中深水的通风。在冰岛海，进一步减少有可能减少向AMOC提供的最密集的溢流水（参考文献8）。
The air-sea transfer of heat and fresh water plays a critical role in the global climate system(1). This is particularly true for the Greenland and Iceland seas, where these fluxes drive ocean convection that contributes to Denmark Strait overflow water, the densest component of the lower limb of the Atlantic Meridional Overturning Circulation (AMOC; ref. 2). Here we show that the wintertime retreat of sea ice in the region, combined with different rates of warming for the atmosphere and sea surface of the Greenland and Iceland seas, has resulted in statistically significant reductions of approximately 20% in the magnitude of the winter air-sea heat fluxes since 1979. We also show that modes of climate variability other than the North Atlantic Oscillation (NAO; refs 3-7) are required to fully characterize the regional air-sea interaction. Mixed-layer model simulations imply that further decreases in atmospheric forcing will exceed a threshold for the Greenland Sea whereby convection will become depth limited, reducing the ventilation of mid-depth waters in the Nordic seas. In the Iceland Sea, further reductions have the potential to decrease the supply of the densest overflow waters to the AMOC (ref. 8).