Studies on the Model Dynamics and Physical Parameterizations of the High-Resolution Version of the Global Climate System Model BCC_CSM

A summary of the development of the high-resolution climate system model, version 2 of the Beijing Climate Center Climate System Model (BCC_CSM2.0), is presented. It is an atmospheric and oceanic fully coupled climate model system with a horizontal resolution of T266 (approximately 45 × 45 km) in the atmosphere and 30 × 30 km in the tropical ocean. It was developed on the basis of a lower resolution version of the model (BCC_CSM1.1) [T42 (approximately 280 × 280 km)]. A more sophisticated atmospheric dynamics framework and physical parameterizations are employed in BCC_CSM2.0, and these improvements enabled the increase in the model’s horizontal resolution. Preliminary evaluations of BCC_CSM2.0 indicate better performance in reproducing regional climate features and the seasonal march of East Asian precipitation, as compared with lower resolution versions. Thirty-year simulations show some improvements in capturing the ITCZ, especially in winter (December to February), the spatial structure and details of East Asian summer monsoon precipitation and surface air temperature, the annual SST cycle in the eastern Pacific, the semiannual cycle in the Western Pacific and their transition phases in the central Pacific.