EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

On the role of the Antarctic Slope Front on the occurrence of theWeddell Sea polynya under climate change

Joseph Lockwood1, Carolina Dufour2, Stephen Griffies3,4, and Michael Winton4
Joseph Lockwood et al.
  • 1Department of Geoscience, Princeton University, USA
  • 2Department of Atmospheric and Oceanic Science, McGill University, Canada
  • 3Program in Atmospheric and Oceanic Science, Princeton University, USA
  • 4National Oceanic and Atmospheric Administration, Geophysical Fluid Dynamics Laboratory, Princeton University, Princeton, New Jersey, USA

This study investigates the occurrence of the Weddell Sea Polynya under an idealized

climate change scenario by evaluating simulations from climate models of different

ocean resolutions. The GFDL-CM2.6 climate model, with roughly 3.8 km

horizontal ocean grid spacing in the high latitudes, forms a Weddell Sea Polynya at

similar time and duration under idealized climate change forcing as under pre-industrial

forcing. In contrast, all convective models forming the fifth phase of the Coupled Model

Intercomparison Project (CMIP5) show either a cessation or a slowdown of Weddell

Sea Polynya events under climate warming. The representation of the Antarctic Slope

Current and related Antarctic Slope Front is found to be key in explaining the

differences between the two categories of models, with these features being more

realistic in CM2.6 than in CMIP5. In CM2.6, the freshwater input driven by sea ice melt

and enhanced runoff found under climate warming largely remains on the shelf region

since the slope front restricts the lateral spread of the freshwater. In contrast, for most

CMIP5 models, open ocean stratification is enhanced by freshening since the absence

of a slope front allows coastal freshwater anomalies to spread into the open ocean.

This enhanced freshening contributes to the slow down the occurrence of Weddell Sea

Polynyas. Hence, an improved representation of Weddell Sea shelf processes in

current climate models is desirable to increase our ability to predict the fate of the

Weddell Sea Polynyas under climate change.

How to cite: Lockwood, J., Dufour, C., Griffies, S., and Winton, M.: On the role of the Antarctic Slope Front on the occurrence of theWeddell Sea polynya under climate change, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1468,, 2021.