Analysis on Effectiveness of SO2 and NO2 Emission Reduction in North China Plain by OMI Data during the Military Parade 2015

During the military parade 2015(September 3rd)，emission control measures were implemented in Beijing and surrounding areas.To evaluate the effect of these measures，we use theplanetary boundary layer SO2 column densities and tropospheric NO2 column densities observed from the satellite instruments OMI in this study.We preprocessed satellite data and calculated the average of time and space from August 1 to September 20 in Beijing，JingJin Ji region and surrounding regions (Shandong，Henan，Shanxi and Inner Mongolia).Finally，we plotted SO2 and NO2 space distributions of Beijing and North China Plain.We analyzed the space distribution of North China Plain SO2 and NO2 concentration during the period of the military parade 2015.It shows that both SO2 column densities and NO2column densities reach the minimum during the period of the across the board emission reductions.Compared to the past three years (2012-2014)，NO2 and SO2 column densities were found to manifest significant reductions over North China Plain.During the period of emission reductions (Aug. 20Sep. 3)，the study showed about 18% and 46% reduction of NO2and SO2 concentration in the JingJin Ji region and decrease of NO2 by 10% and SO2 by 37% in the surrounding regions.However，air quality plummeted after the lifting of local and regional joint emission source control measures.Compared to the past three years，it showed increase of NO2 by 19% and SO2 by 1% in the JingJin Jiregion.SO2 concentration increased by 30% over Beijing especially.It suggests the effectiveness of regional joint emission source control measures.Our study indicates that the emission source control measures were effective in Beijing and surrounding provinces during the military parade.With the advantage of real time and large scale，observation from space could be applied to atmospheric pollution monitoring and assessment of emission control measures.