On the role of the Antarctic Slope Front on the occurrence of theWeddell Sea polynya under climate change
- 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, https://doi.org/10.5194/egusphere-egu21-1468, 2021.
