ENSO and Pacific Decadal Variability in the Community Earth System Model Version 2
ENSO and Pacific Decadal Variability in the Community Earth System Model Version 2
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DOI：
10.1029/2019ms002022
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发表时间：
2020-12-01
影响因子：
6.8
通讯作者：
Larson, S. M.
中科院分区：
文献类型：
--
作者：
Capotondi, A.;Deser, C.;Larson, S. M.
本文介绍了在共同体地球系统模式第2版（CESM2）的工业化前多世纪模拟中厄尔尼诺-南方涛动（ENSO）和太平洋年代际变率（PDV）的描述。该模式较好地模拟了ENSO的几个方面，包括主导时间尺度、热带和温带前兆、El Nino和La Nina事件的复合演变以及ENSO遥相关。模式对ENSO光谱特征的良好表征与模式中赤道纬向风应力异常的空间格局相一致，这使得赤道温跃层按延迟/补给振荡范式调整的时间尺度正确，也反映了赤道暖水量的真实时间演变。模式中的PDV表现出与观测到的非常相似的模式，具有真实的热带和南太平洋特征，而这些特征在一些CESM2前身模式中要弱得多。PDV的热带分量也显示与ENSO年代际调制有关，这与观测结果相似。然而，ENSO振幅比工业化前CESM2模拟中观测到的大30%左右，在历史总体中甚至更大，这可能是人为影响的结果。与观测结果相反，最大的变率出现在太平洋中部而不是东太平洋，这一差异在一定程度上阻碍了模式反映厄尔尼诺空间格局多样性的能力，而且似乎与不切实际地将降水异常局限于西太平洋有关。
This study presents a description of the El Nino-Southern Oscillation (ENSO) and Pacific Decadal Variability (PDV) in a multicentury preindustrial simulation of the Community Earth System Model Version 2 (CESM2). The model simulates several aspects of ENSO relatively well, including dominant timescale, tropical and extratropical precursors, composite evolution of El Nino and La Nina events, and ENSO teleconnections. The good model representation of ENSO spectral characteristics is consistent with the spatial pattern of the anomalous equatorial zonal wind stress in the model, which results in the correct adjustment timescale of the equatorial thermocline according to the delayed/recharge oscillator paradigms, as also reflected in the realistic time evolution of the equatorial Warm Water Volume. PDV in the model exhibits a pattern that is very similar to the observed, with realistic tropical and South Pacific signatures which were much weaker in some of the CESM2 predecessor models. The tropical component of PDV also shows an association with ENSO decadal modulation which is similar to that found in observations. However, the ENSO amplitude is about 30% larger than observed in the preindustrial CESM2 simulation, and even larger in the historical ensemble, perhaps as a result of anthropogenic influences. In contrast to observations, the largest variability is found in the central Pacific rather than in the eastern Pacific, a discrepancy that somewhat hinders the model's ability to represent a full diversity in El Nino spatial patterns and appears to be associated with an unrealistic confinement of the precipitation anomalies to the western Pacific.