Preferred structures in large‐scale circulation and the effect of doubling greenhouse gas concentration in HadCM3
Preferred structures in large‐scale circulation and the effect of doubling greenhouse gas concentration in HadCM3
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HadCM3大尺度环流中的优选结构及温室气体浓度加倍的影响
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发表时间：
2009
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影响因子：
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通讯作者：
A. Turner
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文献类型：
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作者：
A. Hannachi;A. Turner
在哈德利中心气候模型 HadCM3 的两次 100 年模拟中研究并比较了表面压力变化的首选结构。在第一个（控制）模拟中，模型强制使用工业化前的二氧化碳浓度 (1 × CO2)，而在第二个模拟中，模型强制使用双倍的 CO2 浓度 (2 × CO2)。分析北半球冬季（十二月至一月至二月）每日的表面压力。使用多元混合模型来识别首选模式。对于控制模拟，在由前两个主成分跨越的状态空间内以 5% 和 2.5% 显着性水平获得两个显着流态。它们显示了北太平洋/阿留申群岛上空的高压中心与北大西洋上空的低压中心相关，以及相反的情况。对于 2 × CO2 模拟，没有获得这样的行为。在高维状态空间中，流动模式是从两种模拟中获得的。发现它们在控制模拟的 1% 水平和 2 × CO2 模拟的 2.5% 水平上显着。因此，在二氧化碳加倍的情况下，大尺度波浪动力学的状态行为减弱。温室气体浓度加倍不仅会影响制度的发生频率，还会影响模式结构。频率较低的政权会被放大，而频率较高的政权会被削弱。最大的变化是在太平洋上空观察到的，在二氧化碳加倍的情况下，阿留申低气压显着加深。版权所有 © 2008 英国皇家气象学会
Preferred structures in the surface pressure variability are investigated in and compared between two 100‐year simulations of the Hadley Centre climate model HadCM3. In the first (control) simulation, the model is forced with pre‐industrial carbon dioxide concentration (1 × CO2) and in the second simulation the model is forced with doubled CO2 concentration (2 × CO2). Daily winter (December–January–February) surface pressures over the Northern Hemisphere are analysed. The identification of preferred patterns is addressed using multivariate mixture models. For the control simulation, two significant flow regimes are obtained at 5% and 2.5% significance levels within the state space spanned by the leading two principal components. They show a high pressure centre over the North Pacific/Aleutian Islands associated with a low pressure centre over the North Atlantic, and its reverse. For the 2 × CO2 simulation, no such behaviour is obtained. At higher‐dimensional state space, flow patterns are obtained from both simulations. They are found to be significant at the 1% level for the control simulation and at the 2.5% level for the 2 × CO2 simulation. Hence under CO2 doubling, regime behaviour in the large‐scale wave dynamics weakens. Doubling greenhouse gas concentration affects both the frequency of occurrence of regimes and also the pattern structures. The less frequent regime becomes amplified and the more frequent regime weakens. The largest change is observed over the Pacific where a significant deepening of the Aleutian low is obtained under CO2 doubling. Copyright © 2008 Royal Meteorological Society