Retreival of tropospheric nitrogen dioxide vertical column density during the 2008 Summer Olympic Games in Beijing

Nitrogen dioxide (NO₂) plays a very important role among the anthropogenic trace gases. The tropospheric NO₂ vertical column density (VCD) maps derived have been used to study many scientific applications, pollution emissions and pollutant distribution. During the 2008 Summer Olympic Games in Beijing, NO₂ is one main air pollutant which should be monitored. This paper presents the NO₂ inverse algorithm, the Differential Optical Absorption Spectroscopy (DOAS), from satellite measurements and the results using this method. The results show 1) the tropospheric NO₂ VCD in Beijing is about the same as that in other cities nearby in June, 2008; 2) from July 1, the tropospheric NO₂ VCD in Beijing decreases significantly, however, it changes little in other cities nearby; 3) the tropospheric NO₂ VCD in Beijing increases a little in August, 2008, which is much lower than that in other cities around, such as Tianjin, Tangshan.