CMIP5模式对青藏高原中东部夏季降水双极型模拟能力的评估

青藏高原中东部夏季降水主要表现为东北和东南反位相变化的双极型特征。采用经验正交函数(empirical orthogonal function,EOF)分解方法,系统性地评估参与第五次耦合模式比较计划 (Coupled Model Intercomparison Project Phase 5,CMIP5)历史模拟试验的 47 个模式对青藏高原中东部夏季降水双极型变化特征的模拟能力。结果表明,大多数模式基本可以反映青藏高原中东部夏季降水东北部和东南部反位相的变化特征。模式间 EOF 分析结果表明在35°N 以南的东西向模拟偏差是 CMIP5 模式模拟降水空间型态的主要偏差,且大多数模式对时间系数的模拟效果差于空间型态。文中定义了一个综合评估指标 Snew 来定量描述模式对空间型态、时间系数以及方差贡献的综合模拟效果。由定量评估结果来看,MIROC-ESM、HadGEM2-CC 和 ACCESS1-0 (FIO-ESM、 HadGEM2-AO 和 MIROC-ESM-CHEM)模式对观测降水的 EOF1(EOF2)模态的综合模拟能力相对较好,而 GISS 系列模式、CESM1-CAM5 和 MPI-ESM-LR (CMCC-CESM、MPI-ESM-MR 和 GFDL- CM3)模式对观测降水的 EOF1(EOF2)模态的综合模拟效果较差。由 EOF1 和 EOF2 的综合评估结果来看,MIROC-ESM-CHEM模式对观测降水的 EOF1 和 EOF2 模态的综合模拟效果最好。

Evaluation of simulation performance of CMIP5 models for the dipole oscillation of summer precipitation over the central and eastern Tibetan Plateau

The summer precipitation over the central and eastern Tibetan Plateau (TP )is mainlycharacterized by a dipole pattern with seesaw changes in the northeast and southeast. Based on theempirical orthogonal function (EOF)analysis,the abilities of 47 models participating in the CoupledModel Intercomparison Project Phase 5 (CMIP5)historical experiments to simulate the dipole oscillationof summer precipitation over the central and eastern TP are systematically evaluated. The results showsthat most of the models can reproduce the seesaw structure of summer precipitation anomalies in thenortheast and southeast of the central and eastern TP. However,the inter-model EOF analysis shows that the east-west simulation deviation in the south of 35°N stands out as the most prominent deviation ofCMIP5 models in simulating spatial patterns of precipitation. Most of the models are worse at simulatingtime coefficients than spatial patterns. A comprehensive evaluation index Snew is defined to quantitativelydescribe the comprehensive simulation performances of 47 CMIP5 models on spatial patterns,timecoefficients,and variance contribution. From the quantitative evaluation results, MIROC-ESM, HadGEM2-CC,and ACCESS1-0 (FIO-ESM,HadGEM2-AO,and MIROC-ESM-CHEM)models performrelatively well in the comprehensive simulation on EOF1 (EOF2)mode of observed precipitation,whilethe GISS series models,CESM1-CAM5,and MPI-ESM-LR (CMCC-CESM,MPI-ESM-MR,and GFDL-CM3)models have poor comprehensive simulation performance on EOF1 (EOF2)mode of observedprecipitation. Based on the comprehensive evaluation results of EOF1 and EOF2,it is found that MIROC-ESM-CHEM model has the best comprehensive simulation performance on the two leading EOF modes ofobserved summer precipitation over the central and eastern TP.