Diverse Relationship between ENSO and the Northwest Pacific Summer Climate among CMIP5 Models: Dependence on the ENSO Decay Pace
Diverse Relationship between ENSO and the Northwest Pacific Summer Climate among CMIP5 Models: Dependence on the ENSO Decay Pace
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CMIP5 模型中 ENSO 与西北太平洋夏季气候之间的不同关系：对 ENSO 衰减速度的依赖
DOI：
10.1175/jcli-d-16-0365.1
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发表时间：
2017-01-01
影响因子：
4.9
通讯作者：
Tao, Weichen
中科院分区：
文献类型：
--
作者：
Jiang, Wenping;Huang, Gang;Tao, Weichen
利用耦合模式比对计划（CMIP 5）第5阶段37个耦合模式的资料，研究了ENSO衰减夏季期间厄尔尼诺-南方涛动（ENSO）对西北太平洋（NWP）气候的影响。在模拟ENSO-NWP关系时，37个最先进的CGCM存在较大的模式间差异。八个高技能和八个低技能的模型被选中，以探讨偏见是如何产生的。通过对高、低技术模式和观测结果的对比分析发现，ENSO-NWP关系的模拟技术在很大程度上取决于模式能否合理地再现ENSO的衰减速度。在赤道西太平洋（EWP）的暖SST异常偏差被发现持续到ENSO衰减夏季的低技能模式，阻碍了异常反气旋的形成在NWP。进一步的分析表明，这些模式的暖海温距平偏置可能与冷舌的过度西伸有关，冷舌的过度西伸使EWP中的气候纬向SST梯度增大。在西风异常情况下，大的气候学纬向SST梯度会导致低技能模式中纬向平流偏暖，而高技能模式中纬向平流偏暖则会导致低技能模式中EWPSST偏暖。暖海温距平偏置通过触发对流和大气Rossby波加强西太平洋西风异常，进而维持暖海温距平偏置。
The impacts of El NiNo-Southern Oscillation (ENSO) on the northwest Pacific (NWP) climate during ENSO decay summers are investigated based on the outputs of 37 coupled general circulation models (CGCMs) from phase 5 of the Coupled Model Intercomparison Project (CMIP5). Large intermodel spread exists in the 37 state-of-the-art CGCMs in simulating the ENSO-NWP relationship. Eight high-skill and eight low-skill models are selected to explore how the bias arises. By comparing the results among high-skill models, low-skill models, and observations, the simulation skill of the ENSO-NWP relationship largely depends on whether the model can reasonably reproduce the ENSO decay pace. Warm SST anomaly bias in the equatorial western Pacific (EWP) is found to persist into the ENSO decay summer in the low-skill models, obstructing the formation of an anomalous anticyclone in the NWP. Further analysis shows that the warm EWPSST anomaly bias is possibly related to the excessive westward extension of cold tongue in these models, which increases climatological zonal SST gradient in the EWP. Under westerly wind anomalies, the larger climatological zonal SST gradient could lead to warmer zonal advections in the low-skill models than that in the high-skill models, which could lead to warm EWPSST anomaly bias in the low-skill models. And the warm EWP SST anomaly bias could strengthen westerly wind anomalies over the western Pacific by triggering convection and atmospheric Rossby waves, which, in turn, could maintain the warm SST anomaly bias in the EWP.