Evaluation of Northern Hemisphere blocking climatology in the 1 Global Environment Multiscale ( GEM ) model 2
Evaluation of Northern Hemisphere blocking climatology in the 1 Global Environment Multiscale ( GEM ) model 2
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发表时间：
2012
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通讯作者：
E. Dunn‐Sigouin;S. Son
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作者：
E. Dunn‐Sigouin;S. Son
5.在北方阻塞气候学的背景下，评价了全球环境多尺度模式（GEM），即加拿大业务数值模式6在再现大气低频变率方面的性能。通过将一个全面但相对简单的阻塞检测算法应用于20年（1987-2006年）GEM模式在气候模式下的集成，进行了验证。与再分析10的比较表明，尽管模式可以相当好地再现北方半球阻塞气候11，但北大西洋和欧盟12国西部的最大阻塞频率通常被低估，其高峰期从冬末推迟到春季。13这与北太平洋阻塞频率形成对比，北太平洋阻塞频率在所有季节都被高估。阻塞气候学的这些错误表述被发现在很大程度上与气候背景流的偏差有关。模拟的station 16 ary波显示了纬向波数1的季节性延迟和纬向17波数2分量的向东延伸，与阻塞频率偏差一致。然而，北大西洋和太平洋的高频涡旋18一直被低估，表明涡旋场的偏差可能不是北太平洋阻塞偏差的主要原因。21
5 The performance of the Global Environmental Multiscale (GEM) model, the Canadian oper6 ational numerical model, in reproducing atmospheric low-frequency variability is evaluated 7 in the context of Northern Hemisphere blocking climatology. The validation is conducted 8 by applying a comprehensive but relatively simple blocking detection algorithm to a 20-year 9 (1987-2006) integration of the GEM model in climate mode. The comparison to reanalysis 10 reveals that, although the model can reproduce Northern Hemisphere blocking climatology 11 reasonably well, the maximum blocking frequency over the north Atlantic and western Eu12 rope is generally underestimated and its peak season is delayed from late winter to spring. 13 This contrasts with the blocking frequency over the north Pacific which is generally overesti14 mated during all seasons. These misrepresentations of blocking climatology are found to be 15 largely associated with the biases in climatological background flow. The modelled station16 ary waves show a seasonal delay in zonal wavenumber 1 and an eastward extension in zonal 17 wavenumber 2 components consistent with blocking frequency biases. High-frequency eddies 18 are, however, consistently underestimated both in the north Atlantic and Pacific, indicating 19 that the biases in eddy fields might not be the main reason for the blocking biases in the 20 north Pacific. 21