Assessment of Southern Ocean mixed-layer depths in CMIP5 models: Historical bias and forcing response
Assessment of Southern Ocean mixed-layer depths in CMIP5 models: Historical bias and forcing response
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DOI：
10.1002/jgrc.20157
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发表时间：
2013-04
影响因子：
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通讯作者：
J. Sallée;E. Shuckburgh;N. Bruneau;A. Meijers;T. Bracegirdle;Zhaomin Wang
中科院分区：
文献类型：
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作者：
J. Sallée;E. Shuckburgh;N. Bruneau;A. Meijers;T. Bracegirdle;Zhaomin Wang
[1]评估了参加第五次耦合模式相互比较项目（CMIP 5）的气候模式中南大洋冬季深层混合层的发展。深冬对流区是海洋内部通风的关键，在许多研究中，其性质的变化与气候变化有关。与观测相比，他们在气候模型中的模拟一直太浅、太轻，而且向赤道方向移动。浅偏差主要与过量的年平均淡水输入在海面上，过度分层的表层，并防止深对流发展在冬季。相比之下，模拟的未来变化主要与冬季热量损失减少有关，这导致冬季混合层更浅。未来情景下，太平洋海盆的混合层变浅最强烈，这与内部通风水量的减少有关。我们发现一个强大的状态依赖性的混合层深度的未来变化，与更大的未来变浅被模拟的模型具有更大的历史混合层深度。考虑到大多数模型都偏浅，我们预计大多数CMIP5气候模型可能会低估未来冬季混合层变浅，这对热量和二氧化碳等气体的封存以及气候具有重要意义。
[1] The development of the deep Southern Ocean winter mixed layer in the climate models participating in the fifth Coupled Models Intercomparison Project (CMIP5) is assessed. The deep winter convection regions are key to the ventilation of the ocean interior, and changes in their properties have been related to climate change in numerous studies. Their simulation in climate models is consistently too shallow, too light and shifted equatorward compared to observations. The shallow bias is mostly associated with an excess annual-mean freshwater input at the sea surface that over-stratifies the surface layer and prevents deep convection from developing in winter. In contrast, modeled future changes are mostly associated with a reduced heat loss in winter that leads to even shallower winter mixed layers. The mixed layers shallow most strongly in the Pacific basin under future scenarios, and this is associated with a reduction of the ventilated water volume in the interior. We find a strong state dependency for the future change of mixed-layer depth, with larger future shallowing being simulated by models with larger historical mixed-layer depths. Given that most models are biased shallow, we expect that most CMIP5 climate models might underestimate the future winter mixed-layer shallowing, with important implications for the sequestration of heat, and gases such as carbon dioxide, and therefore for climate.