This paper provides the first evidence for sea-ice formation in the Cordillera Darwin (CD) fjords in southern Chile, which is farther north than sea ice has previously been reported for the Southern Hemisphere. Initially observed from a passenger plane in September 2015, the presence of sea ice was then confirmed by aerial reconnaissance and subsequently identified in satellite imagery. A time series of Sentinel-1 and Landsat-8 images during austral winter 2015 was used to examine the chronology of sea-ice formation in the Cuevas fjord. A longer time series of imagery across the CD was analyzed from 2000 to 2017 and revealed that sea ice had formed in each of the 13 fjords during at least one winter and was present in some fjords during a majority of the years. Sea ice is more common in the northern end of the CD, compared to the south where sea ice is not typically present. Is suggested that surface freshening from melting glaciers and high precipitation reduces surface salinity and promotes sea-ice formation within the semi-enclosed fjord system during prolonged periods of cold air temperatures. This is a unique set of initial observations that identify questions for future research in this remote area.

中文翻译：

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智利科迪勒拉达尔文峡湾（54°S）出现海冰的首次记录

本文首次提供了智利南部科迪勒拉达尔文 (CD) 峡湾中海冰形成的证据，该峡湾比之前报道的南半球海冰更北。最初于 2015 年 9 月从一架客机上观察到海冰的存在，随后通过空中侦察确认并随后在卫星图像中发现。使用 2015 年南方冬季的 Sentinel-1 和 Landsat-8 图像时间序列来检查 Cuevas 峡湾海冰形成的年表。从 2000 年到 2017 年，对整个 CD 的较长时间序列的图像进行了分析，结果显示，至少有一个冬季在 13 个峡湾中的每一个都形成了海冰，并且在大部分年份中都存在于一些峡湾中。海冰在 CD 的北端更为常见，与通常不存在海冰的南部相比。建议在长时间的冷空气温度下，冰川融化和高降水造成的地表清新降低了地表盐度并促进了半封闭峡湾系统内的海冰形成。这是一组独特的初步观察结果，确定了该偏远地区未来研究的问题。