Zonally symmetric normal modes associated with the AO/NAM under a seasonally varying background climatology
Zonally symmetric normal modes associated with the AO/NAM under a seasonally varying background climatology
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DOI：
10.1111/j.1600-0870.2006.00204.x
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发表时间：
2006-01
期刊：
影响因子：
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通讯作者：
N. Zhao;M. Takahashi
中科院分区：
文献类型：
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作者：
N. Zhao;M. Takahashi
本文用数值方法研究了纬向对称正模在北极涛动（AO）或北方半球环状模（NAM）中的作用。本文提出了一个关于不同模态之间充分发展的非线性相互作用的简正模选择机制的一般理论，它不仅解释了北方半球AO/NAM的显著性，而且也解释了南半球南极涛动（AAO）的存在。根据这种正常模式的选择机制，纬向对称正常模式的空间结构类似的AO和AAO提取使用ECMWF数据和线性算子的二维模式与季节变化的基本状态。本文还根据这一理论研究了该模态的年际变化。
This paper describes a numerical study of the role of zonally symmetric normal modes in the dynamics of the Arctic Oscillation (AO) or Northern Hemisphere Annular Mode (NAM)with seasonally varying climatological fields. Ageneral theory of the mechanism for normal mode selection involving a fully developed non-linear interaction between different modes is proposed, and this explains not only the prominence of the AO/NAM in the Northern Hemisphere, but also the existence of the Antarctic Oscillation (AAO) in the Southern Hemisphere. Following this normal mode selection mechanism, zonally symmetric normal mode with spatial structures resembling those of the AO and AAO is extracted by use of ECMWF data and the linear operator of a two-dimensional model with a seasonally varying basic state. The interannual variability of this mode is also investigated in the light of this theory.