Increased Occurrence of Stratospheric Sudden Warmings during El Niño as Simulated by WACCM
Increased Occurrence of Stratospheric Sudden Warmings during El Niño as Simulated by WACCM
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DOI：
10.1175/jcli3655.1
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发表时间：
2006-02
影响因子：
4.9
通讯作者：
M. Taguchi;D. Hartmann
中科院分区：
文献类型：
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作者：
M. Taguchi;D. Hartmann
用全大气群落气候模式（WACCM）在常年1月条件下的试验表明，平流层突然变暖（SSW）在厄尔尼诺冬季发生的可能性是拉尼娜冬季的两倍，与有限的观测数据基本一致。模拟厄尔尼诺和拉尼娜的热带海温异常导致平流层逐日变率的概率分布函数（PDF）形状发生变化，导致厄尔尼诺条件下平均极温和涡旋较弱。热带SST强迫引起的响应类似于高纬度对流层上部和平流层纬向波数为1的行星波（波1）增强和波2减弱的观测响应。增强的波1有助于在平流层下部的极向涡动热通量的PDF的移位，或波强迫进入平流层。PDF的移动包括一个强波事件的增加，诱导更多的频率和频率的变化。
Abstract Experiments with Whole Atmosphere Community Climate Model (WACCM) under perpetual January conditions indicate that stratospheric sudden warmings (SSWs) are twice as likely to occur in El Nino winters than in La Nina winters, in basic agreement with the limited observational dataset. Tropical SST anomalies that mimic El Nino and La Nina lead to changes in the shape of probability distribution functions (PDFs) of stratospheric day-to-day variability, resulting in a warmer pole and weaker vortex on average for El Nino conditions. The tropical SST forcing induces a response similar to the observed response in the enhancement of the planetary wave of zonal wavenumber 1 (wave 1) and the weakening of wave 2 in the upper troposphere and stratosphere of high latitudes. The enhanced wave 1 contributes to a shift of the PDFs of poleward eddy heat flux in the lower stratosphere, or wave forcing entering the stratosphere. The shift of the PDFs includes an increase of strong wave events that induce more freque...