Projected changes in summer water vapor transport over East Asia under the1.5℃ and2.0℃ global warming targets

摘要

水汽输送的变化对于降水的变化有重要贡献.基于优选的1 3个CMIP5模式发现:RCP4.5和RCP8.5排放情景下,1.5℃和2.0℃增暖时东亚夏季水汽输送均加强,且2.0℃增暖时模式间一致性更好;水汽含量的增加对东亚南部和北部水汽输送的加强均有贡献,东亚南部水汽输送的加强也与低层环流的加强相联系.0.5℃额外增暖(1.5℃和2.0℃增暖间比较)时,两种排放情景下水汽输送的变化在我国南海与东北地区存在差异,使得两个地区降水变化存在差异;水汽输送的变化与低层环流的变化关系密切,且模式间一致性相对低.%This study investigates changes in summer water vapor transport (WVT) over East Asia under 1.5℃ and 2.0℃ global warming (GW) for the +4.5 and +8.5 W m-2 Representative Concentration Pathway (RCP) scenarios (RCP4.5 and RCP8.5,respectively).Of the 27 models used,18 show better skill in simulating the climatological summer WVT over East Asia of the present day.Of those 18,13 reach 1.5℃ and 2.0℃ GW for the two RCPs.Based on these 13 models,results show that-relative to the present day-the summer WVT is enhanced over East Asia under 1.5℃ and 2.0℃GW for RCP4.5 and RCP8.5.The inter-model consistency is higher under 2.0℃ GW.Increased water vapor content favors the enhanced WVT over both southern and northern East Asia,while lower-level circulation contributes to the enhanced WVT over southern East Asia.Compared to 1.5℃ GW,the summer WVT under 2.0℃ GW is further enhanced over most of East Asia for RCP4.5.For RCP8.5,the summer WVT is also further enhanced over southern East Asia,while this is not the case over northern East Asia.Under the additional 0.5℃ GW,the changes in summer WVT,with low inter-model consistency,are closely related to anomalous lower-level circulation.Precipitation increases over the East China Sea to southern Japan,the Korean Peninsula,and North China,for both RCP4.5 and RCP8.5.However,the changes in precipitation over the South China Sea and Northeast China are different for the two RCPs.This is connected to the difference in the changes of WVT divergence.