Projections of winter polynyas and their biophysical impacts in the Ross Sea Antarctica

• Published in: Climate dynamics Vol. 62; no. 2; pp. 989 - 1012
• Main Authors: DuVivier, Alice K., Molina, Maria J., Deppenmeier, Anna-Lena, Holland, Marika M., Landrum, Laura, Krumhardt, Kristen, Jenouvrier, Stephanie
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.02.2024; Springer; Springer Nature B.V; Springer-Verlag
• Subjects: Algorithms; Antarctic bottom water; Antarctic region; Antarctica; Atmosphere; Atmospheric circulation; Bottom water; climate; Climate change; Climate system; Climatology; Coasts; Commercial fishing; decline; Earth and Environmental Science; Earth Sciences; Earth system science; Environmental aspects; Environmental assessment; exports; Geophysics/Geodesy; heat; Heat flux; Heat transfer; Ice cover; Marine ecosystems; Marine parks; Marine protected areas; Meteorology & Atmospheric Sciences; Net Primary Productivity; Neural networks; Oceanography; Original; Original Article; Polynyas; Primary production; Protected areas; Regions; Sea ice; Sea ice concentrations; Sea ice thickness; Self organizing maps; Substrates; Thickness; Trends; Winter; Antarctica; Ross Sea; Antarctic region; Model; Climate change; Antarctic; Polynya; Sea ice
• ISSN: 0930-7575; 1432-0894; 1432-0894
• DOI: 10.1007/s00382-023-06951-z

This study investigates winter polynyas in the southern Ross Sea, Antarctica where several polynyas are known to form. Coastal polynyas are areas of lower sea ice concentration and/or thickness along the coast that are otherwise surrounded by more extensive, thicker sea ice pack. Polynyas are also locations where organisms can exploit both the ice substrate and pelagic resources. Using a self organizing map algorithm, we identify polynya events in the Community Earth System Model Version 2 Large Ensemble (CESM2-LE). The neural network algorithm is able to identify polynya events without imposing an ice concentration or thickness threshold, as is often done when identifying polynyas. The CESM2-LE produces a wintertime polynya feature comparable in size and location to the Ross Sea polynya, and during polynya events there are large turbulent heat fluxes and export of sea ice from the Ross Sea. In the CESM2-LE polynya event frequency is projected to decrease sharply in the later twentyfirst century, leading to increasing sea ice concentrations and thicknesses in the region. The drivers of the polynya frequency decline are likely both large scale circulation changes and local atmosphere and ocean feedbacks. If declines in wintertime polynya frequency over the twentyfirst century do occur they may impact Antarctic Bottom Water formation and local net primary productivity. Thus, better understanding potential local and unexpected sea ice changes in the Ross Sea is important for both assessing climate system impacts and ecological impacts on the Ross Sea ecosystem, which is currently protected by an internationally recognized marine protected area.