Processes governing the predictability of the Atlantic meridional overturning circulation in a coupled GCM
Processes governing the predictability of the Atlantic meridional overturning circulation in a coupled GCM
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DOI：
10.1007/s00382-011-1025-1
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发表时间：
2011-02
期刊：
影响因子：
4.6
通讯作者：
P. Ortega;E. Hawkins;R. Sutton
中科院分区：
文献类型：
--
作者：
P. Ortega;E. Hawkins;R. Sutton
利用ECHO-G海气耦合模式的长期控制模拟，研究了北大西洋纬向翻转环流（MOC）年代际变化的可预报性过程。我们阐明了当地的随机强迫的大气和其他潜在的海洋过程的作用，并使用我们的结果来建立一个预测回归模型。MOC变率的主要影响来自东拉布拉多海的海气热通量。这种异常和MOC的变化之间的最大相关性发生在提前2年的时间，但我们表明，MOC集成的热通量变化在一段时间内的10年。相应的单变量回归模型占74.5%的年际变化的MOC（后Ekman组件已被删除）。格陵兰-苏格兰海脊以南的密集异常也显示出比翻转变化早4-6年，并提供了第二个预测因子。在包含第二个预测因子的情况下，所得回归模型解释了MOC总方差的82.8%。这最终的双变量模型也在大型快速十年翻转事件进行了测试。快速变化的迹象总是很好地代表了双变量模型，但幅度通常被低估，这表明其他过程也很重要，这些大的快速年代际变化的MOC。
The processes that govern the predictability of decadal variations in the North Atlantic meridional overturning circulation (MOC) are investigated in a long control simulation of the ECHO-G coupled atmosphere–ocean model. We elucidate the roles of local stochastic forcing by the atmosphere, and other potential ocean processes, and use our results to build a predictive regression model. The primary influence on MOC variability is found to come from air–sea heat fluxes over the Eastern Labrador Sea. The maximum correlation between such anomalies and the variations in the MOC occurs at a lead time of 2 years, but we demonstrate that the MOC integrates the heat flux variations over a period of 10 years. The corresponding univariate regression model accounts for 74.5% of the interannual variability in the MOC (after the Ekman component has been removed). Dense anomalies to the south of the Greenland-Scotland ridge are also shown to precede the overturning variations by 4–6 years, and provide a second predictor. With the inclusion of this second predictor the resulting regression model explains 82.8% of the total variance of the MOC. This final bivariate model is also tested during large rapid decadal overturning events. The sign of the rapid change is always well represented by the bivariate model, but the magnitude is usually underestimated, suggesting that other processes are also important for these large rapid decadal changes in the MOC.