Dominant frazil ice production in the Cape Darnley polynya leading to Antarctic Bottom Water formation

Antarctic Bottom Water (AABW) occupies the abyssal layer of the world ocean and contributes to the global overturning circulation. It originates from dense shelf water, which forms from brine rejection during sea ice production. An important region of AABW formation has been identified off the Cape...

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Bibliographic Details
Published in:Science Advances
Main Authors: Ohshima, Kay I., Fukamachi, Yasushi, Ito, Masato, Nakata, Kazuki, Simizu, Daisuke, Ono, Kazuya, Nomura, Daiki, Hashida, Gen, Tamura, Takeshi
Format: Article in Journal/Newspaper
Language:English
Published: American Association for the Advancement of Science (AAAS) 2022
Subjects:
Antarctic
Cape Darnley
Darnley
Antarc*
Sea ice
Online Access:http://dx.doi.org/10.1126/sciadv.adc9174
https://www.science.org/doi/pdf/10.1126/sciadv.adc9174
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Summary:Antarctic Bottom Water (AABW) occupies the abyssal layer of the world ocean and contributes to the global overturning circulation. It originates from dense shelf water, which forms from brine rejection during sea ice production. An important region of AABW formation has been identified off the Cape Darnley polynya. However, it remains unclear why and how high ice production leads to AABW formation. Using moored acoustic measurements and a satellite microwave algorithm, we reveal that underwater frazil ice dominates in the polynya. This underwater ice formation prevents heat-insulating surface-cover ice forming, thereby enabling efficient ice production. The high ice production in the nearshore and longer residence times create high-salinity source water for the AABW. Underwater frazil ice occurs as long as strong winds continue and occasionally penetrates depths of at least 80 m. Deep-penetrating frazil ice is particularly prominent in this polynya, while it also occurs in other Antarctic coastal polynyas.

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