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.

中文翻译：

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冰岛西部和格陵兰海的冬季水团转化

来自冰岛西部和格陵兰海 2018 年冬季调查的水文和速度数据用于调查流入丹麦海峡的溢流水的通风情况。我们专注于两大类溢流水：温暖、咸水的大西洋溢流水 (AtOW) 和寒冷、新鲜的北极溢流水 (ArOW)。前者主要位于东格陵兰海流 (EGC) 内，而后者则位于冰岛和格陵兰海的内部。从北向南前进，在冬季，EGC 中 AtOW 的性质发生了透心变化，而夏季则相反，沿等密度混合占主导地位。使用重复观察记录了水柱对 10 天冷空气爆发的反应。活动期间，北风将EGC的淡水帽推到陆上，和对流改变了水流向海边缘的水。来自 EGC 中 AtOW 核心的热量和盐分的横向转移似乎影响了这种水质量转换。使用一维混合模型研究了内部混合层的长期演变。这表明，在强大气强迫下，ArOW 中密度最大的成分可以在该区域通风。在冬季调查期间观察到从 EGC 产生的许多反气旋涡流，表明这些特征可以在改变/阻止公海对流方面发挥不同的作用。使用一维混合模型研究了内部混合层的长期演变。这表明，在强大气强迫下，ArOW 中密度最大的成分可以在该区域通风。在冬季调查期间观察到从 EGC 产生的许多反气旋涡流，表明这些特征可以在改变/阻止公海对流方面发挥不同的作用。使用一维混合模型研究了内部混合层的长期演变。这表明，在强大的大气强迫下，ArOW 中密度最大的成分可以在该区域通风。在冬季调查期间观察到从 EGC 产生的许多反气旋涡流，表明这些特征可以在改变/阻止公海对流方面发挥不同的作用。