Multidecadal fluctuations of the North Atlantic Ocean and feedback on the winter climate in CMIP5 control simulations
Multidecadal fluctuations of the North Atlantic Ocean and feedback on the winter climate in CMIP5 control simulations
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DOI：
10.1002/2015jd024107
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发表时间：
2016-03
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影响因子：
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通讯作者：
Y. Peings;Graham R. Simpkins;G. Magnusdottir
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作者：
Y. Peings;Graham R. Simpkins;G. Magnusdottir
本研究探讨了大西洋年代际变率（AMV）和北大西洋冬季大气环流之间的关系，在第五耦合模式相互比较项目（CMIP 5）的模拟。内部（使用前工业控制模拟）和外部强制（使用历史和代表性浓度路径8.5模拟）模拟AMV与观察结果的比较表明，CMIP 5模型缺乏内部生成的AMV，除了两个模型（GFDL-ESM 2G和HadGEM 2-ES）。冬季北大西洋涛动（NAO）对AMV的长期影响被确定，但在模式中没有发现AMV对大气环流的一致反馈。然而，GFDL-ESM 2G和HadGEM 2-ES显示了一个小的滞后NAO信号，表明海洋对大气年代际波动的驱动作用，具有两种不同的潜在机制。HadGEM 2-ES表现出大西洋热带辐合带的纬向移动，可以通过从热带发出的Rossby波列调制NAO。在GFDL-ESM 2G中，AMV与风暴轴活动的减少以及季节内天气系统向负NAO系统的转变有关。这些结果带来了希望，北大西洋和周围大陆冬季气候的一些长期可预测性可以从北大西洋的长期海洋波动中提取出来，前提是AMV在耦合的海洋-大气模式中得到正确的表示。
This study examines the relationship between the Atlantic Multidecadal Variability (AMV) and the wintertime atmospheric circulation of the North Atlantic in simulations of the fifth Coupled Model Intercomparison Project (CMIP5). Comparisons of internal (using preindustrial control simulations) and externally forced (using historical and Representative Concentration Pathways 8.5 simulations) simulated AMV with observations suggest that the CMIP5 models lack internally generated AMV, except for two models (GFDL‐ESM2G and HadGEM2‐ES). A long‐term influence of the winter North Atlantic Oscillation (NAO) on the AMV is identified, but no consistent feedback of the AMV onto the atmospheric circulation is found among the models. However, GFDL‐ESM2G and HadGEM2‐ES show a small lagged NAO signal that suggests a driving role of the ocean on decadal fluctuations of the atmosphere, with two different potential mechanisms. HadGEM2‐ES exhibits a latitudinal shift of the Atlantic Intertropical Convergence Zone that can modulate the NAO through a Rossby wave train emanating from the tropics. In GFDL‐ESM2G, the AMV is associated with a decrease in storm track activity and a shift of the intraseasonal weather regimes toward the negative NAO regime. These results raise hope that some long‐term predictability of the winter climate over the North Atlantic and surrounding continents could be extracted from long‐term oceanic fluctuations of the North Atlantic Ocean, provided that the AMV is correctly represented in coupled ocean‐atmosphere models.