Model analysis of soil dust impacts on the boundary layer meteorology and air quality over East Asia in April 2015

Abstract

An online coupled meteorology-chemistry-aerosol model (WRF-Chem) is used to quantify the impact of soil dust on radiative forcing, boundary layer meteorology and air quality over East Asia. The simulation is conducted from 14 to 17 April 2015, when an intense dust storm originated in the Gobi Desert and moved through North China. An integrated comparison analysis using surface observations, satellite, and lidar measurements demonstrates the excellent performance of the WRF-Chem model for meteorological parameters, pollutant concentrations, aerosol optical characteristics, and the spatiotemporal evolution of the dust storm. The maximum aerosol optical depth induced by dust aerosols is simulated to exceed 3.0 over the dust source areas and 1.5 over the downwind regions. Dust has a cooling effect (−1.19Wm−2) at the surface, a warming effect (+0.90Wm−2) in the atmosphere and a relatively small forcing (−0.29Wm−2) at the top of the atmosphere averaged over East Asia from 14 to 17 April 2015. Due to the impact of dust aerosols, the near-surface air temperature is decreased by 0.01°C and 0.06°C in the daytime and increased by 0.13°C and 0.14°C at night averaged over the dust sources and the North China Plain (NCP), respectively. The changes in relative humidity are in the range of −0.38% to +0.04% for dust sources and −0.40% to +0.27% for NCP. The maximum decrease in wind speed of ~0.1ms−1 is found over NCP. The planetary boundary layer height during the daytime exhibits maximum decreases of 16.34m and 41.70m over dust sources and NCP, respectively. The pollutant concentrations are significantly influenced by dust-related heterogeneous chemical reactions, with a maximum decrease of 1.66ppbV for SO2, 7.15ppbV for NOy, 35.04μgm−3 for NO3−, and a maximum increase of 9.47μgm−3 for SO42− over the downwind areas.