Wintertime Water Mass Transformation in the Western Iceland and Greenland Seas
Wintertime Water Mass Transformation in the Western Iceland and Greenland Seas
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DOI：
10.1029/2020jc016893
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发表时间：
2021-08-01
影响因子：
3.6
通讯作者：
Xu, Fanghua
中科院分区：
文献类型：
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作者：
Huang, Jie;Pickart, Robert S.;Xu, Fanghua
来自2018年冰岛西部和格陵兰海冬季调查的水文和速度数据用于调查丹麦海峡溢流水的通风情况。我们重点研究了两类溢出水：暖的、含盐的大西洋溢出水（AtOW）和冷的、新鲜的北极溢出水（ArOW）。前者主要位于东格陵兰海流（EGC）内，而后者则位于冰岛海和格陵兰海的内部。从北到南，EGC中AtOW的性质在冬季是纵向改变的，而在夏季，沿等环流混合占主导地位。利用重复观测记录了水柱对10天冷空气爆发的反应。在此过程中，北风将EGC的淡水帽推到岸上，对流改变了洋流向海边缘的水。EGC中AtOW核心的热量和盐的横向传递似乎对这种水团转变产生了一些影响。利用一维混合模型研究了内部混合层的长期演化过程。这表明，在强烈的大气强迫下，该地区ArOW最密集的组分可以被通风。在冬季调查中观测到大量由EGC产生的反气旋涡旋，揭示了这些特征在改变或阻止公海对流方面可以发挥不同的作用。
Hydrographic and velocity data from a 2018 winter survey of the western Iceland and Greenland Seas are used to investigate the ventilation of overflow water feeding Denmark Strait. We focus on the two general classes of overflow water: warm, saline Atlantic-origin Overflow Water (AtOW) and cold, fresh Arctic-origin Overflow Water (ArOW). The former is found predominantly within the East Greenland Current (EGC), while the latter resides in the interior of the Iceland and Greenland Seas. Progressing north to south, the properties of AtOW in the EGC are modified diapycnally during the winter, in contrast to summer when along-isopycnal mixing dominates. The water column response to a 10-days cold-air outbreak was documented using repeat observations. During the event, the northerly winds pushed the freshwater cap of the EGC onshore, and convection modified the water at the seaward edge of the current. Lateral transfer of heat and salt from the core of AtOW in the EGC appears to have influenced some of this water mass transformation. The long-term evolution of the mixed layers in the interior was investigated using a 1-D mixing model. This suggests that, under strong atmospheric forcing, the densest component of ArOW can be ventilated in this region. Numerous anti-cyclonic eddies spawned from the EGC were observed during the winter survey, revealing that these features can play differing roles in modifying/prohibiting the open-ocean convection.