An assessment of the simulation of East-Asia precipitation in the high-resolution community earth system model

Data analyses of long-term historical experiments using version 1.3 of the Community Earth System Model with 100 km resolution for both atmosphere and ocean (low-resolution, LR), and 25 km resolution for atmosphere and 10 km resolution for ocean (high-resolution, HR), were conducted to study the impact of model horizontal resolution on the simulation of East Asian precipitation. The features analyzed here include long-time mean spatial distribution, intra-seasonal variabilities, and probability of frequency and intensity. Due to the finer grid resolution, the better simulation of convection and water vapor transport conditions, the long-time mean spatial pattern of precipitation in the HR is much closer to the observation compared to the LR simulation, especially the rain belt along the south edge of the Tibetan Plateau associated with complex topography. Although the HR slightly improves the intra-seasonal evolution of East Asian precipitation, on the whole, the inaccurate simulation of circulation characteristics in the middle and upper troposphere amplifies the simulation bias of the rain belt position. The daily time scale precipitation was evaluated by intensity-frequency structure, indicating that the finer resolution makes the simulation more reasonable, especially in monsoon regions. Although there are aspects that need to be further improved in the HR simulation, the HR model bias in East Asian precipitation is overall smaller compared to that of the LR.