Using simulations of the last millennium to understand climate variability seen in palaeo-observations: similar variation of Iceland–Scotland overflow strength and Atlantic Multidecadal Oscillation
Using simulations of the last millennium to understand climate variability seen in palaeo-observations: similar variation of Iceland–Scotland overflow strength and Atlantic Multidecadal Oscillation
复制标题
利用上个千年的模拟来了解古观测中看到的气候变化：冰岛-苏格兰溢流强度和大西洋多年代际振荡的类似变化
DOI：
10.5194/cp-11-203-2015
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发表时间：
2015
影响因子：
4.3
通讯作者：
H. F. Kleiven
中科院分区：
文献类型：
--
作者：
K. Lohmann;J. Mignot;H. Langehaug;J. Jungclaus;D. Matei;O. Otterå;Yongqi Gao;T. L. Mjell;U. Ninnemann;H. F. Kleiven
抽象的。最近对过去600年冰岛-苏格兰溢流强度的古重建表明，其低频变化与大西洋数十年振荡(AMO)的古重建具有很强的相似性。然而，仅基于古重建，这种类似变化的潜在机制仍不清楚。在这项研究中，我们使用三个耦合气候模式对上个千年外力驱动的重建进行模拟，以研究冰岛-苏格兰溢流强度和AMO指数类似变化的可能机制。在模型模拟中也发现了这两个时间序列的相似变化。我们的分析表明，在外强迫模拟中，整个盆地的AMO指数是由低纬海表面温度(SST)变率决定的，而不是由大西洋经向翻转环流(MOC)强度的变化主导的。这一结果表明，通过MOC强度的大尺度联系不足以解释冰岛-苏格兰溢流强度和AMO指数的(模拟)相似变化。相反，通过与AMO指数正相关的北欧海洋表面状态和密度结构对冰岛-苏格兰海脊上的气压梯度的影响，更具局部性的联系是(模拟的)类似变化的原因。在模式模拟中，冰岛-苏格兰溢流强度与AMO指数的相关性较弱，北欧海域的风应力也对溢流强度有影响。我们的研究表明，古气候模拟为理解与相对稀少的古观测有关的机制和大规模联系提供了有用的工具。
Abstract. A recent palaeo-reconstruction of the strength of the Iceland–Scotland overflow during the last 600 years suggests that its low-frequency variability exhibits strong similarity with palaeo-reconstructions of the Atlantic Multidecadal Oscillation (AMO). The underlying mechanism of the similar variation remains unclear, however, based on palaeo-reconstructions alone. In this study we use simulations of the last millennium driven by external forcing reconstructions with three coupled climate models in order to investigate possible mechanisms underlying the similar variation of Iceland–Scotland overflow strength and AMO index. Similar variation of the two time series is also largely found in the model simulations. Our analysis indicates that the basin-wide AMO index in the externally forced simulations is dominated by the low-latitude sea surface temperature (SST) variability and is not predominantly driven by variations in the strength of the Atlantic meridional overturning circulation (MOC). This result suggests that a large-scale link through the strength of the MOC is not sufficient to explain the (simulated) similar variation of Iceland–Scotland overflow strength and AMO index. Rather, a more local link through the influence of the Nordic seas surface state and density structure, which are positively correlated with the AMO index, on the pressure gradient across the Iceland–Scotland ridge is responsible for the (simulated) similar variation. In the model simulation showing a weaker correlation between the Iceland–Scotland overflow strength and the AMO index, the wind stress in the Nordic seas also influences the overflow strength. Our study demonstrates that palaeo-climate simulations provide a useful tool to understand mechanisms and large-scale connections associated with the relatively sparse palaeo-observations.
影响因子：
4.3
作者：
Jungclaus, J. H.;Lorenz, S. J.;Marotzke, J.
通讯作者：
Marotzke, J.
影响因子：
4.6
作者：
Ba, Jin;Keenlyside, Noel S.;Volodin, Evgeny
通讯作者：
Volodin, Evgeny