Is the Atlantic subpolar gyre bistable in comprehensive coupled climate models?
Is the Atlantic subpolar gyre bistable in comprehensive coupled climate models?
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DOI：
10.1007/s00382-012-1525-7
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发表时间：
2013-06-01
期刊：
影响因子：
4.6
通讯作者：
Levermann, Anders
中科院分区：
文献类型：
--
作者：
Born, Andreas;Stocker, Thomas F.;Levermann, Anders
大西洋副极地环流（SPG）是北大西洋年代际气候变化的主要驱动因素之一。在这里，我们分析了 19 个不同的综合耦合气候模型的工业化前控制模拟中的动态。该分析基于最近提出的 SPG 动力学描述，该描述发现，由于 SPG 中心的盐输送和增强的深层对流等正反馈机制，环流可能是双稳态的。我们采用统计方法来识别时间序列中受到强噪声影响的多个平衡点，并分析复合场以评估双稳态是否来自假设的反馈机制。由于噪声在大多数模型中的时间序列中占主导地位，因此只能在六个模型中明确检测到多种循环模式。这六个模型中有四个证实强化是由正反馈机制引起的。
The Atlantic subpolar gyre (SPG) is one of the main drivers of decadal climate variability in the North Atlantic. Here we analyze its dynamics in pre-industrial control simulations of 19 different comprehensive coupled climate models. The analysis is based on a recently proposed description of the SPG dynamics that found the circulation to be potentially bistable due to a positive feedback mechanism including salt transport and enhanced deep convection in the SPG center. We employ a statistical method to identify multiple equilibria in time series that are subject to strong noise and analyze composite fields to assess whether the bistability results from the hypothesized feedback mechanism. Because noise dominates the time series in most models, multiple circulation modes can unambiguously be detected in only six models. Four of these six models confirm that the intensification is caused by the positive feedback mechanism.