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Regional controls on the sea ice-mixed layer depth relationship in the West Antarctic Peninsula (WAP)
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  • Milo Johannes Declan Bischof,
  • Daniel N Goldberg,
  • Sian Frances Henley,
  • Neil J Fraser
Milo Johannes Declan Bischof
University of Edinburgh

Corresponding Author:milo.bischof@ed.ac.uk

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Daniel N Goldberg
University of Edinburgh
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Sian Frances Henley
University of Edinburgh
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Neil J Fraser
Scottish Association For Marine Science
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In the West Antarctic Peninsula (WAP), complex interactions between the cryosphere, ocean and atmosphere produce an environment with large geographical, seasonal and interannual variability which is highly vulnerable to climate change. The seasonal sea ice cycle and its interactions with upper-ocean mixing play an important role in structuring this environment. Here we show that the relationship between sea ice and mixed layer depth (MLD) varies regionally between the WAP shelf and off-shelf regions. Using an MITgcm regional model of the WAP and Bellingshausen Sea for 1989-2018, we find that on the WAP shelf, high winter sea ice coverage is related to shallow spring mixed layers, whereas in a region offshore of the shelf, high winter sea ice coverage is related to deep spring mixed layers. The exact boundary between positive and negative correlations between winter sea ice concentration (SIC) and spring MLD varies decadally. Our results can be explained by a nonlinear relationship between SIC and momentum flux into the ocean, with a minor additional role for the timing of seasonal processes. Transport of sea ice across the model domain dampens this mechanism except in regions of very large sea ice export such as polynyas. With sea ice conditions projected to undergo large changes over the course of the century, understanding the relationship between sea ice and upper-ocean mixing in this unique and vulnerable location is crucial for understanding the wider impacts of climate change on biological productivity in the polar oceans.
02 Aug 2023Submitted to ESS Open Archive
04 Aug 2023Published in ESS Open Archive