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Slow and Intraseasonal Modes of the Boreal Winter Atmospheric Circulation Simulated by CMIP5 Models |
YING Kai-Ran1,2, ZHAO Tian-Bao1, ZHENG Xiao-Gu2 |
1Key Laboratory of Regional Climate-Environment Research for East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
2College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China |
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Abstract The authors evaluate the performance of models from Coupled Model Intercomparison Project Phase 5 (CMIP5) in simulating the historical (1951–2000) modes of interannual variability in the seasonal mean Northern Hemisphere (NH) 500 hPa geopotential height during winter (December-January-February, DJF). The analysis is done by using a variance decomposition method, which is suitable for studying patterns of interannual variability arising from intraseasonal variability and slow variability (time scales of a season or longer). Overall, compared with reanalysis data, the spatial structure and variance of the leading modes in the intraseasonal component are generally well reproduced by the CMIP5 models, with few clear differences between the models. However, there are systematic discrepancies among the models in their reproduction of the leading modes in the slow component. These modes include the dominant slow patterns, which can be seen as features of the Pacific-North American pattern, the North Atlantic Oscillation/Arctic Oscillation, and the Western Pacific pattern. An overall score is calculated to quantify how well models reproduce the three leading slow modes of variability. Ten models that reproduce the slow modes of variability relatively well are identified.
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Received: 18 June 2013
Revised: 31 July 2013
Accepted: 23 August 2013
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Corresponding Author:
ZHAO Tian-Bao
E-mail: zhaotb@tea.ac.cn
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