Assessing mid-latitude dynamics in extreme event attribution systems
Assessing mid-latitude dynamics in extreme event attribution systems
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DOI：
10.1007/s00382-016-3308-z
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发表时间：
2017-06-01
期刊：
影响因子：
4.6
通讯作者：
Allen, Myles
中科院分区：
文献类型：
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作者：
Mitchell, Daniel;Davini, Paolo;Allen, Myles
在目前用于极端事件归因的模型中评价了与极端温度和降水事件有关的大气变化模式。一个100名成员的初始条件集合的全球环流模式HadAM3P进行了比较，从耦合模式相互比较项目，第5阶段（CMIP 5）和CMIP 5大气只对应（AMIP 5）的多模式集合。HadAM3P的使用允许相对快速地计算巨大的集合，从而提供对极端动态的独特见解。分析集中在冬季的中北方大陆（主要是欧洲），并与ERA中期再分析进行了比较。三模态大西洋涡驱动喷流分布是非常好地捕捉HadAM3P，但不是这样的CMIP 5或AMIP 5多模式的平均值，虽然个别型号的票价更好。众所周知，在大西洋地区的阻塞低估是明显的CMIP 5和AMIP 5，也在较小程度上，在HadAM3P。太平洋阻塞特征在所有建模方案中都得到了很好的体现。阻塞持续时间是偏向于模型再现太多的短暂的事件，在所有三个建模系统。在CMIP 5和AMIP 5集合中，大西洋上空的相关风暴路径过于纬向，但在HadAM 3P中模拟得更好，除了在西欧上空太弱。在所有情况下，CMIP5和AMIP5的性能几乎相同，这表明这里考虑的大气模式的偏差与SST没有很强的耦合，也许其他模式的特征，如分辨率更重要。对于事件归因研究，建议只采用能够产生相关动力学现象的模型，而不是对整个CMIP 5或AMIP 5可用模型进行统计。
Atmospheric modes of variability relevant for extreme temperature and precipitation events are evaluated in models currently being used for extreme event attribution. A 100 member initial condition ensemble of the global circulation model HadAM3P is compared with both the multi-model ensemble from the Coupled Model Inter-comparison Project, Phase 5 (CMIP5) and the CMIP5 atmosphere-only counterparts (AMIP5). The use of HadAM3P allows for huge ensembles to be computed relatively fast, thereby providing unique insights into the dynamics of extremes. The analysis focuses on mid Northern Latitudes (primarily Europe) during winter, and is compared with ERA-Interim reanalysis. The tri-modal Atlantic eddy-driven jet distribution is remarkably well captured in HadAM3P, but not so in the CMIP5 or AMIP5 multi-model mean, although individual models fare better. The well known underestimation of blocking in the Atlantic region is apparent in CMIP5 and AMIP5, and also, to a lesser extent, in HadAM3P. Pacific blocking features are well produced in all modeling initiatives. Blocking duration is biased towards models reproducing too many short-lived events in all three modelling systems. Associated storm tracks are too zonal over the Atlantic in the CMIP5 and AMIP5 ensembles, but better simulated in HadAM3P with the exception of being too weak over Western Europe. In all cases, the CMIP5 and AMIP5 performances were almost identical, suggesting that the biases in atmospheric modes considered here are not strongly coupled to SSTs, and perhaps other model characteristics such as resolution are more important. For event attribution studies, it is recommended that rather than taking statistics over the entire CMIP5 or AMIP5 available models, only models capable of producing the relevant dynamical phenomena be employed.