Simulation and Projection of Near-Surface Wind Speeds in China by BCC-CSM Models

We evaluated the ability of the Beijing Climate Center models on different horizontal resolutions (BCC-CSM1.1 on approximately 280-km resolution and BCC-CSM1.1m on approximately 110-km resolution) in simulating the nearsurface wind speeds (NWS) in China during 1961-2005. The spatial distribution of the annual mean NWS over China is better captured by BCC-CSM1.1m than by BCC-CSM1.1 due to the finer resolution. The weakened NWS over China during 1961-2005 cannot be reproduced by BCC-CSM1.1, whereas BCC-CSM1.1m is able to simulate the decreasing trend of the autumn NWS in North China, although the magnitude is about 1/3 of the observed value. This is attributed to the better performance of this finer-resolution model in reproducing the increase in sea level pressure over Mongolia and North China over the past 45 years. The results suggest that increasing the horizontal resolution of the BCC-CSM model has improved its ability in reproducing the spatial distribution and long-term changes of NWS over China. Future projections by BCC-CSM1.1m under different Representative Concentration Pathway (RCP) scenarios demonstrate that the autumn NWS in North China will decrease during the 21st century under both the middle (RCP4.5) and high (RCP8.5) emission scenarios, with a higher decreasing rate under RCP8.5.