Supercooled Southern Ocean Waters
Supercooled Southern Ocean Waters
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DOI：
10.1029/2020gl090242
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发表时间：
2020-10-28
影响因子：
5.2
通讯作者：
Sarmiento, Jorge L.
中科院分区：
文献类型：
--
作者：
Haumann, F. Alexander;Moorman, Ruth;Sarmiento, Jorge L.
在寒冷的极地沃茨中，温度有时会降到冰点以下，这一过程被称为过冷。然而，极地地区的观测挑战限制了我们对这一现象的空间和时间范围的理解。我们在这里提供的观测证据表明，过冷水沃茨是更广泛的季节性冰覆盖的南大洋比以前报道的。在5.8%的所有分析的水文剖面以南的55 ° S，我们发现温度低于表面凝固点（“潜在的”过冷），其中一半的温度低于当地的凝固点（“原位”过冷）。当忽略测量不确定性时，其发生率加倍。我们把深层海岸海洋过冷归因于南极冰架的融化，把季节性海冰区表面诱导的过冷归因于冬季海冰的形成。后者的过冷类型可以延伸到永久密度跃层由于对流下沉羽垂直示踪剂运输和水团结构在极地海洋的一个重要机制。
In cold polar waters, temperatures sometimes drop below the freezing point, a process referred to as supercooling. However, observational challenges in polar regions limit our understanding of the spatial and temporal extent of this phenomenon. We here provide observational evidence that supercooled waters are much more widespread in the seasonally ice-covered Southern Ocean than previously reported. In 5.8% of all analyzed hydrographic profiles south of 55 degrees S, we find temperatures below the surface freezing point ("potential" supercooling), and half of these have temperatures below the local freezing point ("in situ" supercooling). Their occurrence doubles when neglecting measurement uncertainties. We attribute deep coastal-ocean supercooling to melting of Antarctic ice shelves and surface-induced supercooling in the seasonal sea-ice region to wintertime sea-ice formation. The latter supercooling type can extend down to the permanent pycnocline due to convective sinking plumes-an important mechanism for vertical tracer transport and water-mass structure in the polar ocean.