Importance of the Antarctic Slope Current in the Southern Ocean Response to Ice Sheet Melt and Wind Stress Change
Importance of the Antarctic Slope Current in the Southern Ocean Response to Ice Sheet Melt and Wind Stress Change
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DOI：
10.1029/2021jc017608
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发表时间：
2022-05-01
影响因子：
3.6
通讯作者：
Winton, M.
中科院分区：
文献类型：
--
作者：
Beadling, R. L.;Krasting, J. P.;Winton, M.
利用两个耦合气候模式GFDL-CM4和GFDL-ESM4，在工业化前的控制模拟中研究了南大洋对地表风应力和南极融水变化的物理响应，以及两者的联合强迫。融水冷却了除威德尔海以外的所有地区的海洋表面，在威德尔海，风应力使近表层变暖。威德尔海表层对融水的有限敏感性是由于融水通量的空间分布、区域水深和大尺度环流模式。融水强迫主导着南极大陆架的反应，这些模式在南极洲西部产生了截然不同的反应。这种差异是由于平均状态表征和融水驱动的南极斜坡流加速。在CM4中，融化的水被一个良好分解的、强大的和加速的ASC有效地困在大陆架上，这将南极西部大陆架与温暖的近海水域隔离开来，导致强烈的地下冷却。在ESM4，一个较弱且扩散的ASC允许更多的融水逃逸到开阔的海洋，南极西部大陆架不会被孤立，相反，强烈的地下变暖发生了。CM4的结果表明可能存在一种限制未来融化的负反馈机制，而ESM4的结果表明可能存在一种加速融化的正反馈机制。我们的研究结果表明，ASC对控制大陆架变化具有强大的影响，强调了将相互作用冰盖模型与海洋模型耦合起来的重要性，这些模型可以解决这些动力学过程。
We use two coupled climate models, GFDL-CM4 and GFDL-ESM4, to investigate the physical response of the Southern Ocean to changes in surface wind stress, Antarctic meltwater, and the combined forcing of the two in a pre-industrial control simulation. The meltwater cools the ocean surface in all regions except the Weddell Sea, where the wind stress warms the near-surface layer. The limited sensitivity of the Weddell Sea surface layer to the meltwater is due to the spatial distribution of the meltwater fluxes, regional bathymetry, and large-scale circulation patterns. The meltwater forcing dominates the Antarctic shelf response and the models yield strikingly different responses along West Antarctica. The disagreement is attributable to the mean-state representation and meltwater-driven acceleration of the Antarctic Slope Current (ASC). In CM4, the meltwater is efficiently trapped on the shelf by a well resolved, strong, and accelerating ASC which isolates the West Antarctic shelf from warm offshore waters, leading to strong subsurface cooling. In ESM4, a weaker and diffuse ASC allows more meltwater to escape to the open ocean, the West Antarctic shelf does not become isolated, and instead strong subsurface warming occurs. The CM4 results suggest a possible negative feedback mechanism that acts to limit future melting, while the ESM4 results suggest a possible positive feedback mechanism that acts to accelerate melt. Our results demonstrate the strong influence the ASC has on governing changes along the shelf, highlighting the importance of coupling interactive ice sheet models to ocean models that can resolve these dynamical processes.