On the misinterpretation of the North Atlantic Oscillation in CMIP5 models
On the misinterpretation of the North Atlantic Oscillation in CMIP5 models
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DOI：
10.1007/s00382-013-1970-y
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发表时间：
2014-09-01
期刊：
影响因子：
4.6
通讯作者：
Cagnazzo, Chiara
中科院分区：
文献类型：
--
作者：
Davini, Paolo;Cagnazzo, Chiara
利用CMIP 5模式研究了冬季北大西洋涛动（NAO）的表现及其与阻塞和大西洋急流的关系。结果表明，一些国家的最先进的气候模式无法正确地模拟物理过程连接到NAO。对于格陵兰岛上空高纬度阻塞频率被严重低估的模型来说，情况尤其如此。在这些模型中，第一个经验正交函数（EOF 1）的欧洲-大西洋部门可以代表至少三个不同类别的主要模式的变化与不同的流行地区的阻塞发生和急流位移。因此，有可能表明，这种“有偏NAO”与观测中看到的典型NAO的不同动力学过程有关。由于NAO是科学界广泛使用的概念，因此，在分析气候模式时可能导致的NAO的“动力误解”可能对NAO相关研究具有重要意义。这可能与涉及气候情景的情景特别相关，因为这些模拟的NAO对温室气体强迫的反应可能不同。
The representation of the wintertime North Atlantic Oscillation (NAO) and its relationship with atmospheric blocking and the Atlantic jet stream is investigated in a set of CMIP5 models. It is shown that some state-of-the-art climate models are unable to correctly simulate the physical processes connected to the NAO. This is especially true for models with a strongly underestimated frequency of high-latitude blocking over Greenland. In these models the first empirical orthogonal function (EOF1) of the Euro-Atlantic sector can represent at least three different categories of dominant modes of variability associated with different prevalent regions of blocking occurrence and jet stream displacements. It is therefore possible to show that such "biased NAOs" are connected with different dynamical processes with respect to the canonical NAO seen in observations. Since the NAO is a widely used concept in scientific community, the consequent "dynamical misinterpretation" of the NAO that can result when climate models are analyzed may have important implications for the NAO-related studies. This may be especially relevant for the ones involving climate scenarios, since these modeled NAOs may react differently to greenhouse gas forcing.