Simulated and projected relationship between the East Asian winter monsoon and winter Arctic Oscillation in CMIP5 models

摘要

TInterdecadal change in the relationship between the East Asian winter monsoon (EAWM) and the Arctic Oscillation (AO) has been documented by many studies. This study, utilizing the model outputs from phase 5 of the Coupled Model Intercomparison Project (CMIP5), evaluates the ability of the coupled models in CMIP5 to capture the intensified relationship between the EAWM and winter AO since the 1980s, and further projects the evolution of the EAWM–AO relationship during the 21st century. It is found that the observed evolution of the EAWM–AO relationship can be reproduced well by some coupled models (e.g., GFDL-ESM2M, GISS-E2-H, and MPI-ESM-MR). The coupled models’ simulations indicate that the impact of winter AO on the EAWM-related circulation and East Asian winter temperature has strengthened since the 1980s. Such interdecadal change in the EAWM–AO relationship is attributed to the intensified propagation of stationary planetary waves associated with winter AO. Projections under the RCP4.5 and RCP8.5 scenarios suggest that the EAWM–AO relationship is significant before the 2030s and after the early 2070s, and insignificant during the 2060s, but uncertain from the 2030s to the 2050s.摘要观测资料显示，东亚冬季风与同期AO的关系在20世纪80年代发生年代际增强。通过考察CMIP5模式对这一现象的模拟情况，发现GFDL-ESM2M、GISS-E2-H和MPI-ESM-MR这3个模式能够再现EAWM-AO关系的年代际增强。进一步考察这3个模式的集合平均结果（MME）发现，冬季AO对EAWM环流系统以及东亚气温的影响均发生明显的年代际变化。通过考察MME模拟的EP通量结果发现，自20世纪80年代开始，在对流层从高纬度地区传播到副热带地区的EP通量异常明显增强，这是MME模拟结果中EAWM-AO关系发生年代际增强的主要原因。