North Atlantic 20th century multidecadal variability in coupled climate models: sea surface temperature and ocean overturning circulation
North Atlantic 20th century multidecadal variability in coupled climate models: sea surface temperature and ocean overturning circulation
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DOI：
10.5194/os-7-389-2011
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发表时间：
2011-06
期刊：
影响因子：
3.2
通讯作者：
I. Medhaug;T. Furevik
中科院分区：
文献类型：
--
作者：
I. Medhaug;T. Furevik
抽象的。分析了24个最先进的大气-海洋环流模式的输出。这些模式与1850-2000年期间观测到的强迫相结合，作为政府间气候变化专门委员会（IPCC）第四次评估报告的一部分。所有模式都显示出在北大西洋部门类似的观测结果，在多年代际时间尺度上增强的变率，但大西洋多年代际振荡（AMO）和大西洋经向翻转环流（AMOC）的振幅和频率有很大的模型间传播。一般来说，这些模型能够再现观测到的温暖和寒冷事件的地理模式，但不能再现早期变暖（1930年代至1950年代）和随后的寒冷时期（1960年代至1980年代）等阶段。这表明观测到的世纪极端气温主要是由于内在气候变率的偶然阶段性变化，而不是由外部强迫主导的。大多数模式显示了一个现实的结构，在翻转环流，其中一半以上的可用模型有一个平均翻转运输的观测估计范围内的13-24斯维尔德鲁普。与一个比正常更强的AMOC相关联，北大西洋的表面温度增加，海冰范围略有减少。个别模式显示出潜在的十年预测AMO和AMOC之间的关系的基础上，但模式强烈不同意的相位和协变的强度。这使得很难确定共同的机制和评估预测的适用性。
Abstract. Output from a total of 24 state-of-the-art Atmosphere-Ocean General Circulation Models is analyzed. The models were integrated with observed forcing for the period 1850–2000 as part of the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report. All models show enhanced variability at multi-decadal time scales in the North Atlantic sector similar to the observations, but with a large intermodel spread in amplitudes and frequencies for both the Atlantic Multidecadal Oscillation (AMO) and the Atlantic Meridional Overturning Circulation (AMOC). The models, in general, are able to reproduce the observed geographical patterns of warm and cold episodes, but not the phasing such as the early warming (1930s–1950s) and the following colder period (1960s–1980s). This indicates that the observed 20th century extreme in temperatures are due to primarily a fortuitous phasing of intrinsic climate variability and not dominated by external forcing. Most models show a realistic structure in the overturning circulation, where more than half of the available models have a mean overturning transport within the observed estimated range of 13–24 Sverdrup. Associated with a stronger than normal AMOC, the surface temperature is increased and the sea ice extent slightly reduced in the North Atlantic. Individual models show potential for decadal prediction based on the relationship between the AMO and AMOC, but the models strongly disagree both in phasing and strength of the covariability. This makes it difficult to identify common mechanisms and to assess the applicability for predictions.