The impact of stochastic physics on the El Niño Southern Oscillation in the EC-Earth coupled model
The impact of stochastic physics on the El Niño Southern Oscillation in the EC-Earth coupled model
复制标题
EC-地球耦合模型中随机物理对厄尔尼诺南方涛动的影响
DOI：
10.1007/s00382-019-04660-0
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发表时间：
2018
期刊：
影响因子：
4.6
通讯作者：
P. Davini
中科院分区：
文献类型：
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作者：
Chunxue Yang;H. Christensen;S. Corti;J. von Hardenberg;P. Davini
在一个EC-Earth耦合气候模式中，研究了随机物理过程对ENSO的影响。通过比较三个成员的控制历史模拟与三个系综成员，包括随机物理在大气中，我们发现，在EC-Earth的随机物理的实施改善了过于薄弱的代表性ENSO。具体而言，厄尔尼诺现象和拉尼娜现象的幅度都有所增加，但幅度较小。随机物理学还改善了厄尔尼诺/南方涛动在年际时间尺度上的时间变异性，这表现在功率谱出现了周期为5-7年和3-4年的峰值。基于与理想化的具有随机噪声的延迟振荡器模型（DO）的行为的类比，我们发现当大气-海洋耦合较小时（大），ENSO的振幅随着噪声振幅的放大而增大（减小）。因此，在欧洲共同体-地球控制运行中被低估的厄尔尼诺/南方涛动变率和随机物理学引起的相关放大可能与过于微弱的大气-海洋耦合相一致。大气中随机物理的激活增加了西风爆发（WWB）的发生（即噪声振幅的放大），这可能引发更多和更强的厄尔尼诺事件（即ENSO振荡的增加）在耦合的EC-地球模式。对EC-Earth模式的平均状态偏差的进一步分析表明，热带太平洋中部的冷海温和干降水偏差以及热带太平洋西部的暖海温和湿降水偏差是导致热带太平洋耦合反馈偏差（弱耦合）的主要原因，而这种耦合反馈偏差与弱ENSO模拟有关。在未来的情景实验（RCP 8.5强迫）中对ENSO行为进行了同样的分析，强调在具有极暖SST的耦合模式中，以强耦合为特征，随机物理对ENSO表示的影响是相反的。这证实了热带太平洋地区的平均状态偏差是EC-Earth中ENSO表现不足的主要原因的假设。
The impact of stochastic physics on El Niño Southern Oscillation (ENSO) is investigated in the EC-Earth coupled climate model. By comparing an ensemble of three members of control historical simulations with three ensemble members that include stochastics physics in the atmosphere, we find that in EC-Earth the implementation of stochastic physics improves the excessively weak representation of ENSO. Specifically, the amplitude of both El Niño and, to a lesser extent, La Niña increases. Stochastic physics also ameliorates the temporal variability of ENSO at interannual time scales, demonstrated by the emergence of peaks in the power spectrum with periods of 5–7 years and 3–4 years. Based on the analogy with the behaviour of an idealized delayed oscillator model (DO) with stochastic noise, we find that when the atmosphere–ocean coupling is small (large) the amplitude of ENSO increases (decreases) following an amplification of the noise amplitude. The underestimated ENSO variability in the EC-Earth control runs and the associated amplification due to stochastic physics could be therefore consistent with an excessively weak atmosphere–ocean coupling. The activation of stochastic physics in the atmosphere increases westerly wind burst (WWB) occurrences (i.e. amplification of noise amplitude) that could trigger more and stronger El Niño events (i.e. increase of ENSO oscillation) in the coupled EC-Earth model. Further analysis of the mean state bias of EC-Earth suggests that a cold sea surface temperature (SST) and dry precipitation bias in the central tropical Pacific together with a warm SST and wet precipitation bias in the western tropical Pacific are responsible for the coupled feedback bias (weak coupling) in the tropical Pacific that is related to the weak ENSO simulation. The same analysis of the ENSO behaviour is carried out in a future scenario experiment (RCP8.5 forcing), highlighting that in a coupled model with an extreme warm SST, characterized by a strong coupling, the effect of stochastic physics on the ENSO representation is opposite. This corroborates the hypothesis that the mean state bias of the tropical Pacific region is the main reason for the ENSO representation deficiency in EC-Earth.
影响因子：
4.9
作者：
Lloyd, James;Guilyardi, Eric;Weller, Hilary
通讯作者：
Weller, Hilary