The sources of Antarctic bottom water in a global ice–ocean model
The sources of Antarctic bottom water in a global ice–ocean model
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全球冰海模型中南极底层水的来源
DOI：
10.1016/s1463-5003(00)00017-2
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发表时间：
2001
期刊：
影响因子：
3.2
通讯作者：
B. Tartinville
中科院分区：
文献类型：
--
作者：
H. Goosse;J. Campin;B. Tartinville
南极底层水（AABW）的形成有两种机制。第一个，可能也是最重要的一个，是由南极大陆架在冰形成期间释放的盐水引发的，这是造成盐度增加的原因。在陆架坡折处与环境水混合后，这些含盐和稠密的水沿着陆架斜坡下沉，侵入全球海洋的最深处。对于第二种情况，表层水密度的增加是由于海洋-大气界面的强烈冷却，以及盐水释放的贡献。这就引起了深层对流和深层沃茨的更新。这两种机制的相对重要性进行了研究，在全球冰-海耦合模式。该模型模拟的氯氟烃（CFC）浓度与观测结果相比毫不逊色，这表明南大洋的深水通风合理，但靠近南极洲的浓度太高。两个人工被动示踪剂释放在南极大陆架表面和在公海允许清楚地表明，这两种机制有助于显着更新的AABW的模式。这表明在我们的模拟中高估了开阔海洋对流。额外的实验表明，由于密集的陆架沃茨的出口AABW生产量是相当敏感的参数化的下坡和中尺度涡的影响。然而，陆架沃茨总是对深水更新作出重大贡献。另外，增加公关。Gent，J.C. McWilliams [Journal of Physical Oceanography 20（1990）150-155]厚度扩散几乎可以抑制公海对流形成AABW。
Two mechanisms contribute to the formation of Antarctic bottom water (AABW). The first, and probably the most important, is initiated by the brine released on the Antarctic continental shelf during ice formation which is responsible for an increase in salinity. After mixing with ambient water at the shelf break, this salty and dense water sinks along the shelf slope and invades the deepest part of the global ocean. For the second one, the increase of surface water density is due to strong cooling at the ocean–atmosphere interface, together with a contribution from brine release. This induces deep convection and the renewal of deep waters. The relative importance of these two mechanisms is investigated in a global coupled ice–ocean model. Chlorofluorocarbon (CFC) concentrations simulated by the model compare favourably with observations, suggesting a reasonable deep water ventilation in the Southern Ocean, except close to Antarctica where concentrations are too high. Two artificial passive tracers released at surface on the Antarctic continental shelf and in the open-ocean allow to show clearly that the two mechanisms contribute significantly to the renewal of AABW in the model. This indicates that open-ocean convection is overestimated in our simulation. Additional experiments show that the amount of AABW production due to the export of dense shelf waters is quite sensitive to the parameterisation of the effect of downsloping and meso-scale eddies. Nevertheless, shelf waters always contribute significantly to deep water renewal. Besides, increasing the P.R. Gent, J.C. McWilliams [Journal of Physical Oceanography 20 (1990) 150–155] thickness diffusion can nearly suppress the AABW formation by open-ocean convection.