Climate impacts of recent multidecadal changes in Atlantic Ocean Sea Surface Temperature: a multimodel comparison
Climate impacts of recent multidecadal changes in Atlantic Ocean Sea Surface Temperature: a multimodel comparison
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DOI：
10.1007/s00382-009-0571-2
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发表时间：
2010-06-01
期刊：
影响因子：
4.6
通讯作者：
Zhou, Tianjun
中科院分区：
文献类型：
--
作者：
Hodson, Daniel L. R.;Sutton, Rowan T.;Zhou, Tianjun
在20世纪，大西洋的海面温度表现出显著的年代际变化。这些变化的来源还没有被严格地确定，但是它们对气候的影响是可以调查的。在这里，我们报告了一组多模式实验，以研究北大西洋变暖模式的影响，以及来自观测的南大西洋冷却模式，这是大西洋年代际振荡（AMO）正相的特征。这些实验是用六个大气环流模型（包括一个模型的两个版本）进行的，主要目标是评估不同模型之间关键气候影响的一致程度。主要的气候影响出现在北美洲和南美洲，对美国和南美洲北方部分陆地的影响最大。这些反应似乎是由一个离赤道吉尔响应加勒比地区的非绝热加热，由于该区域内的降雨量增加和北移的热带辐合带（ITCZ），由于异常的越赤道SST梯度的组合。大多数模型显示，美国陆地温度升高，夏季平均海平面压力（JJA）降低，以应对北大西洋变暖和南大西洋凉爽，与观测结果一致。然而，大多数模型显示，美国夏季降雨量没有显着影响。在南美洲北方，所有模式显示南半球冬季（JJA）降雨量减少，而夏季（DJF）降雨量普遍增加。然而，有一个很大的传播模型之间的降雨量异常的幅度在陆地上。在美洲以外，没有一致的重要模拟反应。特别是北大西洋涛动（NAO）在北大西洋和欧洲冬季（DJF）没有显着变化。此外，在非洲降雨中观察到的萨赫勒干燥信号在模拟响应中没有看到。这表明，与一些研究相反，大西洋几十年振荡不是萨赫勒地区降雨量最近减少的主要驱动因素。
During the twentieth century sea surface temperatures in the Atlantic Ocean exhibited prominent multidecadal variations. The source of such variations has yet to be rigorously established-but the question of their impact on climate can be investigated. Here we report on a set of multimodel experiments to examine the impact of patterns of warming in the North Atlantic, and cooling in the South Atlantic, derived from observations, that is characteristic of the positive phase of the Atlantic Multidecadal Oscillation (AMO). The experiments were carried out with six atmospheric General Circulation Models (including two versions of one model), and a major goal was to assess the extent to which key climate impacts are consistent between the different models. The major climate impacts are found over North and South America, with the strongest impacts over land found over the United States and northern parts of South America. These responses appear to be driven by a combination of an off-equatorial Gill response to diabatic heating over the Caribbean due to increased rainfall within the region and a Northward shift in the Inter Tropical Convergence Zone (ITCZ) due to the anomalous cross-equatorial SST gradient. The majority of the models show warmer US land temperatures and reduced Mean Sea Level Pressure during summer (JJA) in response to a warmer North Atlantic and a cooler South Atlantic, in line with observations. However the majority of models show no significant impact on US rainfall during summer. Over northern South America, all models show reduced rainfall in southern hemisphere winter (JJA), whilst in Summer (DJF) there is a generally an increase in rainfall. However, there is a large spread amongst the models in the magnitude of the rainfall anomalies over land. Away from the Americas, there are no consistent significant modelled responses. In particular there are no significant changes in the North Atlantic Oscillation (NAO) over the North Atlantic and Europe in Winter (DJF). Additionally, the observed Sahel drying signal in African rainfall is not seen in the modelled responses. Suggesting that, in contrast to some studies, the Atlantic Multidecadal Oscillation was not the primary driver of recent reductions in Sahel rainfall.