Emerging impact of Greenland meltwater on deepwater formation in the North Atlantic Ocean
Emerging impact of Greenland meltwater on deepwater formation in the North Atlantic Ocean
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DOI：
10.1038/ngeo2740
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发表时间：
2016-07-01
影响因子：
18.3
通讯作者：
Bamber, Jonathan L.
中科院分区：
文献类型：
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作者：
Boening, Claus W.;Behrens, Erik;Bamber, Jonathan L.
自20世纪90年代以来，格陵兰冰盖的质量损失不断增加（1,2）。由于表面融化和出口冰川排放导致的淡水通量增加，在亚北极大西洋不断变化的淡水收支中起着越来越重要的作用（3）。从格陵兰持续且不断增加的淡水通量进入表层海洋，可能会抑制拉布拉多海冬季的深层对流，这对大西洋经向翻转环流的强度可能产生影响（4 - 6）。在此，我们利用一个网格间距足够精细的全球海洋环流模型来评估淡水通量增加的影响，该模型能够捕捉北大西洋副极地地区的小尺度涡旋输送过程，淡水通量是用全空间分辨率重建的（3）。我们的模拟结果表明，西格陵兰陆架融水的侵入已使拉布拉多海表层开始出现逐渐变淡的趋势。尽管变淡程度仍小于与偶发性“大盐度异常”相关的变化，但融水的积累可能会变得足够大，在未来几年逐渐抑制冬季深层对流。我们得出结论，淡水异常尚未对大西洋经向翻转环流产生重大影响。
The Greenland ice sheet has experienced increasing mass loss since the 1990s(1,2). The enhanced freshwater flux due to both surface melt and outlet glacier discharge is assuming an increasingly important role in the changing freshwater budget of the subarctic Atlantic(3). The sustained and increasing freshwater fluxes from Greenland to the surface ocean could lead to a suppression of deep winter convection in the Labrador Sea, with potential ramifications for the strength of the Atlantic meridional overturning circulation(4-6). Here we assess the impact of the increases in the freshwater fluxes, reconstructed with full spatial resolution(3), using a global ocean circulation model with a grid spacing fine enough to capture the small-scale, eddying transport processes in the subpolar North Atlantic. Our simulations suggest that the invasion of meltwater from the West Greenland shelf has initiated a gradual freshening trend at the surface of the Labrador Sea. Although the freshening is still smaller than the variability associated with the episodic 'great salinity anomalies', the accumulation of meltwater may become large enough to progressively dampen the deep winter convection in the coming years. We conclude that the freshwater anomaly has not yet had a significant impact on the Atlantic meridional overturning circulation.