Seasonal variations of anthropogenic sulfate aerosol and direct radiative forcing over China

Regional climate model (RegCM2) and sulfur transport model (NJUADMS) were combined to simulate the distribution of anthropogenic sulfate aerosol burden over China, where a “look up table” method was applied to illustrate sulfate formation from SO2-oxidation. Direct radiative forcing of sulfate aerosol was further estimated using the scheme suggested by Charlson et al (1991). Investigations show that the annual average total sulfate column over mainland China is 2.01 mg/m2 with high value in East and Central areas (more than 7 mg/m2). The annual average direct radiative forcing of China is about −0.85 W/m2. The forcing can reach −7 W/m2 in Central and East China during the winter season. Total sulfate column shows significant seasonal variations with winter maximum-summer minimum in the Southern part of China and spring maximum-autumn minimum in the northern part of China. Strong seasonal cycles of direct radiative forcing are also found due to the influence of total sulfate column, cloud, relative humidity and the reflectivity of underlying surface