Zonal Distribution of Circumpolar Deep Water Transformation Rates and Its Relation to Heat Content on Antarctic Shelves
Zonal Distribution of Circumpolar Deep Water Transformation Rates and Its Relation to Heat Content on Antarctic Shelves
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南极陆架环极深水转化率的地带性分布及其与热含量的关系
DOI：
10.1029/2022jc019310
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Roquet, Fabien
中科院分区：
文献类型：
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作者：
Narayanan, Aditya;Gille, Sarah T.;Mazloff, Matthew R.;du Plessis, Marcel D.;Murali, K.;Roquet, Fabien
我们分析了15年的观测数据和5年的南大洋模式模拟，以量化环极深水（CDW）的转化速率和相关的地表热损失。本研究发现，在东南极洲、威德尔海和罗斯海的大陆架上，地表浮力通量将约4.4 Sv的地表水转化为CDW，为CDW向地表散失热量提供了途径。此外，约6.6 Sv的CDW混合在Weddell和Ross亚极环流的地表水中。相反，强化的分层抑制了CDW等平线的露头，使其在大陆架上的转化率降低了约8倍，在阿蒙森海和别令斯豪森海的深海上的转化率降低了约3倍。CDW在侵入大陆架时保持其近海温暖特性，导致那里的底部温度升高。这一分析证明了次极环流过程对侵蚀CDW和促进大陆架进一步转化的重要性，显著减少了进入冰架锋面的热量。这种遮蔽效应在威德尔海西部最强，向东减弱，这有助于解释大陆架底部温度和南极冰架融化速度的巨大地带性差异。
We analyze 15‐year of observational data and a 5‐year Southern Ocean model simulation to quantify the transformation rates of Circumpolar Deep Water (CDW) and the associated heat loss to the surface. This study finds that over the continental shelves of East Antarctica and the Weddell and Ross Seas, surface buoyancy fluxes transform ∼4.4 Sv of surface waters into CDW, providing a path for CDW to lose heat to the surface. In addition, ∼6.6 Sv of CDW are mixed with surface waters in the Weddell and Ross subpolar gyres. In contrast, enhanced stratification inhibits the outcropping of CDW isopycnals, reducing their transformation rates by a factor of ∼8 over the continental shelf and by a factor of ∼3 over the deeper ocean in the Amundsen and Bellingshausen Seas. The CDW retains its offshore warm properties as it intrudes over the continental shelves, resulting in elevated bottom temperatures there. This analysis demonstrates the importance of processes in subpolar gyres to erode CDW and to facilitate further transformation on the continental shelves, significantly reducing the heat able to access ice shelf fronts. This sheltering effect is strongest in the western Weddell Sea and tends to diminish toward the east, which helps explain the large zonal differences in continental‐shelf bottom temperatures and the melt rates of Antarctic ice shelves.