CMIP5模式对东太平洋ITCZ偶极子模态模拟能力的评估

本研究利用第五次国际间耦合模式比较计划(Coupled Model Intercomparison Project phase 5, CMIP5)中的24个模式的工业革命前控制试验(Pre-industrial Control, picontrol)模拟结果, 结合观测资料, 评估了24个CMIP5 模式对东太平洋热带辐合带偶极子(Eastern Pacific ITCZ dipole, EPID)降水模态的模拟能力, 并建立了其与模式对热带太平洋气候态模拟之间的联系。结果表明: 1) 绝大多数模式在北半球春季(2—4月)对EPID模态模拟能力较差, 主要原因在于CMIP5模式对热带辐合带(Intertropical Convergence Zone, ITCZ)的模拟偏差, 其中模拟效果较差的模式在2—4月的气候态降水分布在赤道以南, 且降水普遍偏强; 2) 对各模式的EPID模态选取的季节按照技巧评分最高进行调整后, 大部分模式能较好地模拟出EPID模态的空间分布特点, 技巧评分在0.6以上, 其中模拟效果好的模式(技巧评分大于0.7)中EPID模态出现的月份同时在中东太平洋气候态表现出“双ITCZ”特征, 且多模式集合结果的模拟误差小于绝大多数模式。

Assessment of eastern Pacific ITCZ dipole mode simulations by CMIP5 models

Based on the Pre-industrial Control (picontrol) experiments from 24 Coupled Model Intercomparison Project (CMIP5) models, we assessed these models’ capability in simulating the eastern Pacific ITCZ dipole (EPID) mode and its linkage with models’ climatological simulation capability. The main results are as follows. (1) Most of the CMIP5 models cannot well reproduce the spatial pattern of the EPID mode in February-April (FMA), because of the common biases of modeled Intertropical Convergence Zone (ITCZ), which is mainly located south of the equator during FMA. (2) After seasonal adjustment according to the highest skillscore of EPID mode, the spatial distribution of the EPID mode in most models is more consistent with that in observations. The models with skillscore above 0.7 can simulate the "double ITCZ" climatological precipitation feature during the EPID season. Additionally, the error of the multi-model ensemble (MME) is smaller than that of most CMIP5 models.