Signals of El Niño Modoki in the tropical tropopause layer and stratosphere
Signals of El Niño Modoki in the tropical tropopause layer and stratosphere
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DOI：
10.5194/acp-12-5259-2012
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发表时间：
2012-06
影响因子：
6.3
通讯作者：
F. Xie;J. Li;W. Tian;Juan Feng;Y. Huo
中科院分区：
文献类型：
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作者：
F. Xie;J. Li;W. Tian;Juan Feng;Y. Huo
利用欧洲中期天气预报中心（ECMWF）再分析资料、海洋厄尔尼诺指数和一般气候模式输出，研究了厄尔尼诺Modoki事件对热带对流层顶（TTL）和平流层的影响。厄尔尼诺-莫多基事件对西太平洋和东太平洋的对流活动有抑制作用，而对中太平洋和北方太平洋的对流活动有增强作用。结果表明，在El Ni Nano Modoki事件期间，西太平洋和东太平洋对流层上层出现负水汽异常，而中太平洋和北方太平洋对流层上层则出现正水汽异常。出射长波辐射（OLR）和对流层高层水汽异常的空间分布均呈三极型。对OLR和对流层高层水汽异常的经验正交函数（ERF）分析表明，典型的El Ni事件与ERF的主导模态相关联，El Ni的Modoki事件与ERF的第二模态相对应。基于ERA中期资料的合成分析表明，与典型的ElNi-Morno事件相比，ElNi-Morno Modoki事件对中高纬平流层的影响是反向的，即：在ElNi-Modoki事件期间，北方极涡较强、较冷，而南方极涡较弱、较暖。模拟结果表明，对中高纬平流层的反作用是由东位相准两年振荡（QBO）信号与厄尔尼诺现象相互作用的复杂结果
The effects of El Ni˜ no Modoki events on the tropical tropopause layer (TTL) and on the stratosphere were investigated using European Center for Medium Range Weather Forecasting (ECMWF) reanalysis data, oceanic El Ni˜ no indices, and general climate model outputs. El Ni ˜ no Modoki events tend to depress convective activities in the western and eastern Pacific but enhance convective activities in the central and northern Pacific. Consequently, during El Ni˜ no Modoki events, negative water vapor anomalies occur in the western and eastern Pacific upper troposphere, whereas there are positive anomalies in the central and northern Pa- cific upper troposphere. The spatial patterns of the outgo- ing longwave radiation (OLR) and upper tropospheric wa- ter vapor anomalies exhibit a tripolar form. The empirical orthogonal function (EOF) analysis of the OLR and upper tropospheric water vapor anomalies reveals that canonical El Nievents are associated with the leading mode of the EOF, while El Ni˜ no Modoki events correspond to the second mode. The composite analysis based on ERA-interim data indicate that El Ni ˜ no Modoki events have a reverse effect on middle-high latitudes stratosphere, as compared with the ef- fect of typical El Ni ˜ no events, i.e., the northern polar vortex is stronger and colder but the southern polar vortex is weaker and warmer during El Ni˜ no Modoki events. According to the simulation' results, we found that the reverse effect on the middle-high latitudes stratosphere is resulted from a compli- cated interaction between quasi-biennial oscillation (QBO) signal of east phase and El Ni ˜