Variation of the summer westerly jet in East Asia during the last deglaciation

The variation of the upper-level subtropical westerly jet over East Asia (EASWJ) in summer during the last deglaciation (LD) and its impact on precipitation distributions in China are investigated using a set of transient simulation. The results show that the EASWJ variability during the LD is characterized by a millennial variation along with a weakening trend. The millennial variation of the EASWJ can lead to a north-south dipole precipitation pattern in eastern China and a uniform precipitation pattern in northern China. The weakening trend of the EASWJ is accompanied with a tripole precipitation pattern in eastern China and a uniform precipitation pattern in northern China. The millennial EASWJ variability is related to the millennial AMOC variability, which is induced by the meltwater flux. The weakening trend is attributed to the warming trend induced by the orbital parameters. Due to the different warming structure, the EASWJ change driven by the greenhouse gas, which is strengthening, is different from that driven by the orbital parameters, although they both tend to lead to a warming trend. Our findings may have implications to better understanding the regional westerly jet variation in response to global climate change, especially the global warming.