Projected changes of wintertime synoptic-scale transient eddy activities in the East Asian eddy-driven jet from CMIP5 experiments

Abstract

The wintertime East Asian eddy-driven jet (EAEJ) responding to climate change in the 21st century is studied using model outputs from the Coupled Model Intercomparison Project phase 5 (CMIP5). Compared to the location displacement in oceanic eddy-driven jets, the magnitude change of synoptic-scale transient eddy activities, measured by eddy kinetic energy (EKE), is a more striking feature in EAEJ. An intensified EKE is projected unanimously by CMIP5 models, suggesting that potential strong winter storm events are likely to happen in East Asian midlatitude in a warming climate. The future change of EKE in EAEJ can be understood in terms of growing baroclinicity wave. The upper level EKE is highly correlated to the low-level static stability, Brunt-Väisälä frequency (BVF). CMIP5 models generally project an intensified upper evel EKE with a reduced low-level BVF (ΔEKE-ΔBVF). Meanwhile, the enhancement of EKE is also constrained by its historical state (ΔEKE-EKE). Intermodel variabilities among CMIP5 models reveal a similar but weaker relationship between ΔBVF (or EKE) and ΔEKE, indicating relatively large model diversities and independencies among CMIP5 models.