Numerical study of aerosol effect on three types of clouds and precipitation in Beijing area

Abstract

Three types of rainfall (storm, moderate and slight rainfall) in the Beijing area were simulated by the Weather Research and Forecast (WRF3.2) model coupled with Milbrandt-two-moment cloud microphysics scheme, to explore the effect of aerosols on clouds and precipitation under continental and maritime aerosol scenarios. Results indicate that an increase of aerosols has various effects on clouds and precipitation. (1) The amount of surface precipitation is obviously affected. With an increase of aerosol concentration, the 48-hr total precipitation of storm and moderate rainfall decreased by 23% and 16.6%, respectively, and the 24-hr total precipitation of slight rainfall decreased by 14.0%. (2) The distribution of surface precipitation is also clearly affected. The average precipitation for a rain storm increases in most parts of western Beijing and decreases by more than 20 mm in most parts of eastern Beijing with increasing aerosol concentration. The average precipitation of moderate rainfall decreases by 0.1–5 mm in most parts of the Beijing area. The effect of increased aerosol concentration is weak for slight rainfall distribution in the study area. (3) With an increase of aerosol concentration, a narrower width and lower precipitation peak value are found in the storm rainfall, and its duration is prolonged for the high aerosol concentration. An earlier precipitation termination of moderate rainfall is found with increasing aerosol concentration. (4) The upper-air hydrometeors vary with aerosol concentration. For storm and moderate rainfall, significantly higher cloud water concentration and lower rain water were found under the continental aerosol scenario.