Observations of supercooled water and frazil ice formation in an Arctic coastal polynya from moorings and satellite imagery
Observations of supercooled water and frazil ice formation in an Arctic coastal polynya from moorings and satellite imagery
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DOI：
10.3189/2015aog69a839
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发表时间：
2015-01-01
影响因子：
2.9
通讯作者：
Eicken, Hajo
中科院分区：
文献类型：
--
作者：
Ito, Masato;Ohshima, Kay I.;Eicken, Hajo
2009/10年冬季，利用系泊的盐度/温度传感器和冰剖面声纳（IPS）数据沿着卫星数据，研究了美国阿拉斯加州巴罗附近楚科奇海沿海冰间湖的过冷水和冰碛冰的形成。来自两个系泊处的海洋学数据显示，当冰间湖开放时，在30-40米深度可能发生过冷事件，包括原位过冷的可能性。我们确定了frazil冰状信号的IPS数据下降到5-15米的深度，与大量的热损失和多风，湍流条件下，在一个活跃的冰间湖。这可能是IPS首次在海洋环境中观察到的冰。在冰碛冰最大信号的当天，星载合成孔径雷达显示冰间湖内有高后向散射条纹，表明在停泊点的下风处有活跃的冰碛冰形成。此外，尽管系泊地点没有冰间湖活动，但持续1-3周的长期潜在过冷发生了两次。这些事件发生在东北向流占主导地位的时期。在这些事件之前，系泊地点西南部形成了一系列沿海冰穴。因此，具有潜在过冷的水团可能是从这些冰穴平流而来。
Formation of supercooled water and frazil ice was studied in the Chukchi Sea coastal polynya off Barrow, Alaska, USA, in winter 2009/10, using moored salinity/temperature sensors and Ice Profiling Sonar (IPS) data along with satellite data. Oceanographic data from two moorings revealed episodic events of potential supercooling at 30-40 m depth, including the possibility of in situ supercooling, while the polynya was open. We identified frazil ice-like signals in the IPS data down to 5-15 m depth, associated with large heat loss and windy, turbulent conditions in an active polynya. This likely represents the first IPS observation of frazil ice in the marine environment. On the day of the maximum signal of frazil ice, spaceborne synthetic aperture radar shows streaks of high backscatter within the polynya, indicating active frazil ice formation just downwind of the mooring sites. In addition, the longer-term potential supercooling that persisted for 1-3 weeks occurred twice despite the absence of polynya activity at the mooring sites. These events occurred during periods dominated by the northeastward current. A series of coastal polynyas had formed southwest of the mooring sites prior to these events. Thus, the water masses with potential supercooling were likely advected from these polynyas.