East Asian summer monsoon dynamics in past and future warm climates: Mid-Piacenzian versus RCP4.5 scenario

Speaker : Yong Sun

Mid-Piacenzian (MP), the most recent interval within the Pliocene (3.264 to 3.025 Ma) known to have 2~3℃ temperatures above preindustrial (PI) levels. It offers an attarctive test bed, with a past warm climate case, 
to investigate atmospheric dyanmics of future anthropogenic warming scenario. However, the physics and dynamics underlying such analogue are neither well understood nor accurately represented by state-of-th-art 
climate models.  This study compares the dynamics of East Asian summer monsoon (EASM) between the past (MP) and future (RCP4.5 scenario) warm climates, with emphasize on physical processes and mechanisms behind the 
monsoon variation. It is shown that EASM precipitation increases in both MP and RCP4.5 scenario. A further step in understanding such a variation consists of a decomposition into dynamical and thermodynamical 
contributions. Thermodynamical processes contribute to the enhancement of EASM precipitation in both cases, while dynamical processes associated with atmospheric circulation changes differ significantly in 
the variation of EASM precipitation in the two warm climates. It is furthermore revealed that the thermodynamical control shapes the large-scale similarity, while dynamical processes play a more important 
role in local differences between the two warm climates.