Wind‐Driven Freshwater Export at Cape Farewell
Wind‐Driven Freshwater Export at Cape Farewell
复制标题
风驱动的告别角淡水出口
DOI：
10.1029/2021jc018309
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
de Jong, M. F.
中科院分区：
文献类型：
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作者：
Duyck, E.;Gelderloos, R.;de Jong, M. F.
格陵兰岛冰融化和北极向亚极地北大西洋输入的淡水增加可能会加强深对流区域的分层并影响翻转环流。然而，从东格陵兰大陆架到深对流区的淡水路径尚未完全了解。我们调查的强风事件在告别角的作用，从东格陵兰电流的Irminger海驱动表面淡水。使用高分辨率模式和大气再分析，我们识别强风事件，并调查其对淡水输出的影响。西风尖端射流与最强和最深的淡水出口横跨陆架，平均37.5毫希沃特的淡水在第一个100米（参考盐度34.9）。这些风事件使等盐线倾斜，并将锋面延伸到近海，特别是在Eirik岭。温和的西风事件与较弱的出口整个shelfbreak（平均值为15.9毫西弗），但总体上有助于更多的淡水出口全年，包括在夏季，当货架是特别新鲜。粒子跟踪表明，一半的表面沃茨跨越shelfbreak在尖端射流事件出口远离货架，要么进入Irminger环流，或被驱动在Eirik岭。在强烈的西风事件，海冰从海岸分离，转向Irminger海，但海冰的贡献，淡水出口在shelfbreak是最小的液态淡水出口相比，由于有限的海冰覆盖在告别角。
Increased freshwater input to the Subpolar North Atlantic from Greenland ice melt and the Arctic could strengthen stratification in deep convection regions and impact the overturning circulation. However, freshwater pathways from the east Greenland shelf to deep convection regions are not fully understood. We investigate the role of strong wind events at Cape Farewell in driving surface freshwaters from the East Greenland Current to the Irminger Sea. Using a high‐resolution model and an atmospheric reanalysis, we identify strong wind events and investigate their impact on freshwater export. Westerly tip jets are associated with the strongest and deepest freshwater export across the shelfbreak, with a mean of 37.5 mSv of freshwater in the first 100 m (with reference salinity 34.9). These wind events tilt isohalines and extend the front offshore, especially over Eirik Ridge. Moderate westerly events are associated with weaker export across the shelfbreak (mean of 15.9 mSv) but overall contribute to more freshwater export throughout the year, including in summer, when the shelf is particularly fresh. Particle tracking shows that half of the surface waters crossing the shelfbreak during tip jet events are exported away from the shelf, either entering the Irminger Gyre, or being driven over Eirik Ridge. During strong westerly wind events, sea ice detaches from the coast and veers toward the Irminger Sea, but the contribution of sea ice to freshwater export at the shelfbreak is minimal compared to liquid freshwater export due to limited sea ice cover at Cape Farewell.