Assessment of Southern Ocean water mass circulation and characteristics in CMIP5 models: Historical bias and forcing response
Assessment of Southern Ocean water mass circulation and characteristics in CMIP5 models: Historical bias and forcing response
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DOI：
10.1002/jgrc.20135
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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;T. Roy
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;T. Roy
[1]在水团框架下研究了参与第五次耦合模式比较项目(CMIP5)的模式描述南大洋水文特征及其倾覆的能力。模型在整个水柱上都有一致的温光偏向。最大的偏差出现在通风层，其体积由模式层和中间层控制。据观察，通风层具有强烈的气候变化指纹，并通过隔离大量的热量和二氧化碳来影响气候。模式水层在模式中的代表性较差，模式水和中间水都有明显的新鲜度偏差。在辐射强迫增加的情况下，模型模拟了整个水柱的变暖和变轻，这再次在通风层最大，突出了这些层对于将气候信号传播到深海的重要性。虽然不同模型之间水团倾覆的强度相对一致，但与基于观测的重建相比，它们在浅层到中等深度的倾覆率略大，而在水柱深处的倾覆率较低。在辐射强迫增强的情况下，大气通量增加了模拟的上层单体翻转的速率，但这种增加被包括混合层水平混合在内的昼夜通量所抵消，并且基本为零。
[1] The ability of the models contributing to the fifth Coupled Models Intercomparison Project (CMIP5) to represent the Southern Ocean hydrological properties and its overturning is investigated in a water mass framework. Models have a consistent warm and light bias spread over the entire water column. The greatest bias occurs in the ventilated layers, which are volumetrically dominated by mode and intermediate layers. The ventilated layers have been observed to have a strong fingerprint of climate change and to impact climate by sequestrating a significant amount of heat and carbon dioxide. The mode water layer is poorly represented in the models and both mode and intermediate water have a significant fresh bias. Under increased radiative forcing, models simulate a warming and lightening of the entire water column, which is again greatest in the ventilated layers, highlighting the importance of these layers for propagating the climate signal into the deep ocean. While the intensity of the water mass overturning is relatively consistent between models, when compared to observation-based reconstructions, they exhibit a slightly larger rate of overturning at shallow to intermediate depths, and a slower rate of overturning deeper in the water column. Under increased radiative forcing, atmospheric fluxes increase the rate of simulated upper cell overturning, but this increase is counterbalanced by diapycnal fluxes, including mixed-layer horizontal mixing, and mostly vanishes.