Antarctic Bottom Water and North Atlantic Deep Water in CMIP6 models
Antarctic Bottom Water and North Atlantic Deep Water in CMIP6 models
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CMIP6 模型中的南极底层水和北大西洋深水
DOI：
10.5194/os-2020-66
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发表时间：
2020
期刊：
影响因子：
3.2
通讯作者：
C. Heuzé
中科院分区：
文献类型：
--
作者：
C. Heuzé
抽象的。深水和底层水的形成是全球海洋环流的重要组成部分，但在上一代气候模型中没有得到很好的反映。我们在这里量化了南极底层水(AABW)和北大西洋深水(NADW)的形成、性质、输送和全球范围的偏差，在35个气候模型中参与了最新的气候模型国际比较项目(CMIP6)。几个CMIP6模式通过陆架过程正确地形成了AABW，但南大洋的28个模式和北大西洋的所有35个模式通过太深、太频繁和/或太大的面积形成了深海和底层水。对流最小的模型形成最准确的AABW，但最不准确的NADW。带有溢出参数的四个CESM2模型是最精确的模型之一。在大西洋，夏季风越冷，S 30∘ 时的深海倾覆越强，夏季风越向北延伸。NADW越咸，大西洋经向翻转环流(AMOC)越强，NADW层越向南延伸。相比之下，在印度洋和太平洋，无论深海倾覆的强度有多大，最新鲜的模式都是延伸最远的模式，最可能的原因是它们也是南极绕极洋流中锋面最弱的模式。自CMIP5以来有了明显的改进：几个CMIP6模式正确地表示或参数化了南极陆架过程，较少的模式显示了南大洋的深对流，更多的模式在拉布拉多海的正确位置对流，海底密度偏差减少，深海倾覆更现实。然而，还需要更多的改进，例如，通过推广溢流参数化的使用，或者通过耦合到交互式冰盖模型，在深水和底层水形成之前，从而准确地表示热量和碳储存。
Abstract. Deep and bottom water formation are crucial components of the global ocean circulation, yet they were poorly represented in the previous generation of climate models. We here quantify biases in Antarctic Bottom Water (AABW) and North Atlantic Deep Water (NADW) formation, properties, transport, and global extent in 35 climate models that participated in the latest Climate Model Intercomparison Project (CMIP6). Several CMIP6 models are correctly forming AABW via shelf processes, but 28 models in the Southern Ocean and all 35 models in the North Atlantic form deep and bottom water via open-ocean deep convection too deeply, too often, and/or over too large an area. Models that convect the least form the most accurate AABW but the least accurate NADW. The four CESM2 models with their overflow parameterisation are among the most accurate models. In the Atlantic, the colder the AABW, the stronger the abyssal overturning at 30∘ S, and the further north the AABW layer extends. The saltier the NADW, the stronger the Atlantic Meridional Overturning Circulation (AMOC), and the further south the NADW layer extends. In the Indian and Pacific oceans in contrast, the fresher models are the ones which extend the furthest regardless of the strength of their abyssal overturning, most likely because they are also the models with the weakest fronts in the Antarctic Circumpolar Current. There are clear improvements since CMIP5: several CMIP6 models correctly represent or parameterise Antarctic shelf processes, fewer models exhibit Southern Ocean deep convection, more models convect at the right location in the Labrador Sea, bottom density biases are reduced, and abyssal overturning is more realistic. However, more improvements are required, e.g. by generalising the use of overflow parameterisations or by coupling to interactive ice sheet models, before deep and bottom water formation, and hence heat and carbon storage, are represented accurately.
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影响因子：
4.9
作者：
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