Abstract: The Community Atmosphere Model Version 3 (CAM3.0)'s simulation ability was evaluated by comparing its simulation results with the related satellite observation data. It was found that the CAM3.0 is able to satisfactorily reproduce the main characters of cloud distribution and its seasonal variations. The direct climate effect of sulfate aerosols on hydrological cycle was investigated through coupling the sulfate cycle with radiation and dynamic processes. The changes in the mass concentration and distribution of sulfate aerosols were simulated well. Sulfate aerosol's effects on hydrological cycle are different in different seasons and regions: the effect in the Northern Hemisphere is greater than that in the Southern Hemisphere in summer because the sulfate mass concentration is greater in the Northern Hemisphere. The trends of changes in cloud fraction, precipitation, and special humidity are mostly similar, indicating that there are close relationships among them.

Key words: sulfate aerosol, hydrological cycle, cloud fraction, precipitation, special humidity