Strong heat loss and brine release during sea ice formation in coastal polynyas act to cool and salinify waters on the Antarctic continental shelf. Polynya activity thus both limits the ocean heat flux to the Antarctic Ice Sheet and promotes formation of Dense Shelf Water (DSW), the precursor to Antarctic Bottom Water. However, despite the presence of strong polynyas, DSW is not formed on the Sabrina Coast in East Antarctica and in the Amundsen Sea in West Antarctica. Using a simple ocean model driven by observed forcing, we show that freshwater input from basal melt of ice shelves partially offsets the salt flux by sea ice formation in polynyas found in both regions, preventing full-depth convection and formation of DSW. In the absence of deep convection, warm water that reaches the continental shelf in the bottom layer does not lose much heat to the atmosphere and is thus available to drive the rapid basal melt observed at the Totten Ice Shelf on the Sabrina Coast and at the Dotson and Getz ice shelves in the Amundsen Sea. Our results suggest that increased glacial meltwater input in a warming climate will both reduce Antarctic Bottom Water formation and trigger increased mass loss from the Antarctic Ice Sheet, with consequences for the global overturning circulation and sea level rise.

中文翻译：

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冰川融水的清新作用增强了冰架的融化，并减少了南极底水的形成。

沿海多尼亚海海冰形成过程中大量的热损失和盐水释放，使南极大陆架上的水变凉和盐化。因此，Polynya活动既限制了海洋向南极冰原的热通量，又促进了密集架水（DSW）的形成，而密集架水是南极底水的前身。然而，尽管存在强烈的多年生菌，但在南极东部的萨布丽娜海岸和南极西部的阿蒙森海却没有形成DSW。使用由观测到的强迫驱动的简单海洋模型，我们显示了来自冰架基础融化的淡水输入部分抵消了两个地区发现的多年生藻类中海冰形成的盐通量，从而阻止了全深度对流和DSW的形成。在没有深对流的情况下，到达底层大陆架的温水不会向大气损失太多热量，因此可用于驱动在萨布丽娜海岸的托滕冰架以及阿蒙森的多森和盖茨冰架上观察到的快速基础融化。海。我们的结果表明，在气候变暖的情况下增加的冰川融水输入量将减少南极底部水的形成，并引发南极冰盖的质量损失增加，从而对全球翻转环流和海平面上升产生后果。