Inter-model Spread of the Changes in the East Asian Summer Monsoon System in CMIP5/6 Models

摘要

Among the state-of-the-art Coupled Model Inter-comparison Project Phase 5 and 6 (CMIP5/6) models, there is considerable inter-model spread in the projected changes in the East Asian summer monsoon (EASM) and its components, including the three-dimensional atmospheric circulation, western North Pacific subtropical high (WNPSH), and East Asian upper-tropospheric westerly jet (EAJ). In this study, we extracted the leading inter-model mode of the EASM changes based on the atmospheric circulation, and investigated its relationship with the WNPSH and EAJ. The leading mode of circulation, characterized as a low-level cyclonic circulation change, is closely correlated with a weakened or eastward-retreated WNPSH and a southward-shifted EAJ. This systematic link between them is maintained by the stronger tropospheric warming over East Asia and the western North Pacific, which originates from the greater surface warming over the equatorial western Pacific.