On the role of the Antarctic Slope Front on the occurrence of theWeddell Sea polynya under climate change
<p>This study investigates the occurrence of the Weddell Sea Polynya under an idealized</p><p>climate change scenario by evaluating simulations from climate models of different</p><p>ocean resolutions. The GFDL-CM2.6 climate model, with roughly 3.8 km</p><p>horizontal ocean grid spacing in the high latitudes, forms a Weddell Sea Polynya at</p><p>similar time and duration under idealized climate change forcing as under pre-industrial</p><p>forcing. In contrast, all convective models forming the fifth phase of the Coupled Model</p><p>Intercomparison Project (CMIP5) show either a cessation or a slowdown of Weddell</p><p>Sea Polynya events under climate warming. The representation of the Antarctic Slope</p><p>Current and related Antarctic Slope Front is found to be key in explaining the</p><p>differences between the two categories of models, with these features being more</p><p>realistic in CM2.6 than in CMIP5. In CM2.6, the freshwater input driven by sea ice melt</p><p>and enhanced runoff found under climate warming largely remains on the shelf region</p><p>since the slope front restricts the lateral spread of the freshwater. In contrast, for most</p><p>CMIP5 models, open ocean stratification is enhanced by freshening since the absence</p><p>of a slope front allows coastal freshwater anomalies to spread into the open ocean.</p><p>This enhanced freshening contributes to the slow down the occurrence of Weddell Sea</p><p>Polynyas. Hence, an improved representation of Weddell Sea shelf processes in</p><p>current climate models is desirable to increase our ability to predict the fate of the</p><p>Weddell Sea Polynyas under climate change.</p>