Uncertainty of central China summer precipitation and related natural internal variability under global warming of 1 to 3°C.

This study examines the response of summer precipitation over central China to global warming via the 50‐member large‐ensemble simulations conducted with the Canadian Earth System Model Version 2. It is found that the model ensemble mean summer precipitation stagnates under warming of 1 to 3°C, while precipitation increases rapidly over central China after 3°C of warming. This phenomenon indicates a strong nonlinear relationship between precipitation change and global warming, and the effects due to natural internal variability are more substantial than those of CO2 forcing in the early warming stage. We further examine the factors responsible for the large uncertainty of the precipitation projection over central China under warming of 1 to 3°C. For the members producing a precipitation increase over central China, the geopotential height and sea level pressure changes show a positive North Atlantic Oscillation–like trend pattern over the North Atlantic and a southeastward propagating atmospheric teleconnection from the North Atlantic to China. The atmospheric teleconnection from the mid–high‐latitude Atlantic to China provides diverging winds in the upper troposphere, causing ascending motion, and contributes to increased precipitation over central China. Besides, an El Niño‐like trend pattern of sea surface temperature (SST) is apparent in the preceding winter, which could contribute to the formation a low‐level anticyclone trend over the western North Pacific (WNP) in the subsequent summer via modulating the SST anomalies in the Indian and Atlantic oceans. The northward water vapour transport in the western part of the anticyclone also favours increased precipitation in central China. The above processes also apply to decreased precipitation, except with opposite signs of anomalies. This study highlights the combined contributions of mid–high‐latitude teleconnection and the WNP anticyclone related to tropical Pacific SST to the uncertainty in the projection of precipitation over central China. [ABSTRACT FROM AUTHOR]