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The seasonal footprinting mechanism in large ensemble simulations of the second generation Canadian earth system model: uncertainty due to internal climate variability
Climate Dynamics ( IF 4.6 ) Pub Date : 2020-07-30 , DOI: 10.1007/s00382-020-05396-y
Shangfeng Chen , Bin Yu

Previous studies indicated that the wintertime North Pacific Oscillation (NPO) could exert marked impacts on the following winter El Niño-Southern Oscillation (ENSO) via the seasonal footprinting mechanism (SFM). Here, we examine this winter NPO-ENSO relationship in a 50-member ensemble of historical simulations conducted with the Canadian Centre for Climate Modeling and Analysis second generation Canadian Earth System Model (CanESM2) over the period of 1950–2005. The observed NPO pattern, featured by a meridional dipole atmospheric anomaly over the North Pacific, can be well reproduced by all of the 50 ensemble members. The multi-member ensemble (MME) mean can well simulate the observed NPO-ENSO relationship, as well as the SFM process. However, there exists a large spread of the results among the 50 members due to internal climate variability. Internal climate variability influences the winter NPO-ENSO relationship through modulating the subtropical center of the NPO. Specifically, the ensemble members with high NPO-ENSO correlations tend to have strong atmospheric anomalies over the subtropical North Pacific in winter. The atmospheric circulation anomaly brings strong sea surface temperature and precipitation anomalies in the tropical central Pacific and westerly wind anomalies over the tropical western Pacific in the following spring. These anomalies sustain in the following seasons and eventually lead to ENSO events in the following winter.



中文翻译:

第二代加拿大地球系统模型的大型整体模拟中的季节足迹机制:由于内部气候变化而导致的不确定性

先前的研究表明,冬季的北太平洋涛动(NPO)可能通过季节性足迹机制(SFM)对随后的冬季厄尔尼诺-南方涛动(ENSO)产生显着影响。在这里,我们在1950-2005年期间与加拿大气候建模与分析中心第二代加拿大地球系统模型(CanESM2)进行的具有50个成员的历史模拟合集中,考察了这个冬季NPO-ENSO的关系。观测到的NPO模式具有北太平洋子午线偶极子大气异常的特征,所有50个合奏成员都可以很好地再现这种模式。多成员合奏(MME)平均值可以很好地模拟观察到的NPO-ENSO关系以及SFM过程。但是,由于内部气候的变化,结果在50个成员中存在很大的差异。内部气候变化通过调节NPO的亚热带中心影响冬季NPO-ENSO关系。具体而言,具有高NPO-ENSO相关性的合奏成员在冬季倾向于在亚热带北太平洋上具有强烈的大气异常。大气环流异常带来热带中部太平洋强烈的海面温度和降水异常,并于次年春天在热带西太平洋上空产生西风异常。这些异常现象在接下来的季节持续存在,并最终在接下来的冬天导致ENSO事件。具有高NPO-ENSO相关性的合奏成员在冬季倾向于在亚热带北太平洋上具有强烈的大气异常。大气环流异常带来热带中部太平洋强烈的海面温度和降水异常,并于次年春天在热带西太平洋上空产生西风异常。这些异常现象在接下来的季节持续存在,并最终在接下来的冬天导致ENSO事件。具有高NPO-ENSO相关性的合奏成员在冬季倾向于在亚热带北太平洋上具有强烈的大气异常。大气环流异常带来热带中部太平洋强烈的海面温度和降水异常,并于次年春天在热带西太平洋上空产生西风异常。这些异常现象在接下来的季节持续存在,并最终在接下来的冬天导致ENSO事件。

更新日期:2020-09-20
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