Indirect radiative forcing and climatic effect of the anthropogenic nitrate aerosol on regional climate of China

Abstract

The regional climate model (RegCM3) and a tropospheric atmosphere chemistry model (TACM) were coupled, thus a regional climate chemistry modeling system (RegCCMS) was constructed, which was applied to investigate the spatial distribution of anthropogenic nitrate aerosols, indirect radiative forcing, as well as its climatic effect over China. TACM includes the thermodynamic equilibrium model ISORROPIA and a condensed gas-phase chemistry model. Investigations show that the concentration of nitrate aerosols is relatively high over North and East China with a maximum of 29 µg m−3 in January and 8 µg m−3 in July. Due to the influence of air temperature on thermodynamic equilibrium, wet scavenging of precipitation and the monsoon climate, there are obvious seasonal differences in nitrate concentrations. The average indirect radiative forcing at the tropopause due to nitrate aerosols is −1.63 W m−2 in January and −2.65 W m−2 in July, respectively. In some areas, indirect radiative forcing reaches −10 W m−2. Sensitivity tests show that nitrate aerosols make the surface air temperature drop and the precipitation reduce on the national level. The mean changes in surface air temperature and precipitation are −0.13 K and −0.01 mm d−1 in January and −0.09 K and −0.11 mm d−1 in July, respectively, showing significant differences in different regions.