未来气候变化背景下Hadley环流变化是一个众所关注的问题。RCP4.5是中等程度的温室气体排放情景，到21世纪末全球增温介于2～3℃之间，这与中上新世暖期(距今约3百万年前)在全球增温方面非常相似，因此基于中上新世暖期和RCP4.5情景下Hadley环流变化特征的比较，揭示Hadley环流变化机理，并预估其气候影响，这对理解未来气候预估结果的不确定性有重要意义。本项目将首先比较参加中上新世模拟比较计划(PlioMIP1)的大气环流模式(AGCM)和耦合模式(CGCM)模拟的Hadley环流变化异同，在此基础之上，揭示主导中上新世暖期Hadley环流强度和边界变化的机理，并将其与主导RCP4.5情景下Hadley环流强度和边界变化的机理比较。与此同时，揭示中上新世暖期和RCP4.5情景下Hadley环流变化各自对东亚气候的影响，特别是阐明Hadley环流变化与EASM环流变化的联系。

The projection of future changes in HC has been much concerned. The mid-Pliocene warm period is considered the most accessible example of a world analogous to the RCP4.5 projected warming at the end of this century, as the mean global temperatures are estimated to be 2–3℃ above pre-industrial temperatures. By performing a comparative study of the HC changes in the context of mid-Pliocene and RCP4.5, it is of vital importance to fully understand the mechanisms of the HC changes and its potential impact on regional climate as well as the uncertainties in future climate projection. In this project, we first examine the similarities and differences of mid-Pliocene HC changes in coupled model and in atmospheric model participating in PlioMIP1, and then demonstrate the dominant mechanism for the changes in HC intensity and edges in mid-Pliocene. By comparison the dominant mechanism for HC changes in mid-Pliocene with than in RCP4.5 scenario, this strengthens the idea that the mid-Pliocene could be a useful tool for understanding HC changes in the future.