Numerical Simulation of the SO2 and NO2 Dry Deposition in Beijing under Stagnant Weather Conditions during the Beijing Olympic Games Period

With the meteorological and contaminated information from Beijing 325m meteorological tower in the Institute of Atmospheric Physics, Chinese Academy of Sciences, and the gas dry deposition resistance model, the influencing factors of the dry deposition，the dry deposition rate，and the dry deposition flux in Beijing before and during the Beijing Olympic Games were calculated. The results show: 1）With the variations of the stability，the solar radiation intensity，and the style of the surface, the SO2 and NO2 dry deposition rates change obviously, and the apparent resistance is the main factor impacting the dry deposition rate. 2）The dry deposition rate and flux during the daytime are greater than those during the nighttime. 3）The dry deposition can remove 24 t SO2 and 55.2 t NO2 in Beijing area in one day before the Beijing Olympic Games, and can remove 10.8 t SO2 and 50.4 t NO2 in one day during the Beijing Olympic Games. This means that the emission reduction measures taken by the Chinese government during the Olympic Games have had a significant effect.