Inversion Of SO₂ And O₃ Column Concentration Based On Observed Solar Spectrum

Sulfur dioxide is one of the major pollutants in the atmosphere and the main reason of acid rain. High concentration of sulfur dioxide will cause great harm to the natural environment and the human health. On the other hand, the reduction of ozone concentration in the atmospheric stratosphere will enlarge the solar ultraviolet radiation that the earth receives, destroying the ecological environment and affecting the normal survival of human and organic matter. Therefore, it is particularly important to monitor the variation of these two gases in the vertical column concentration. Monitoring atmospheric pollutants in spectroscopic methodology is superior to that in chemical method, characterized by high efficiency, fast response and no secondary pollutants.In this paper,, the solar spectrum and the sky scattering spectrum of the in Nanjing were observed and analyzed based on the existing research and theory by high precision spectrometer iHR320. The results showed that the there were many absorptive peaks in solar spectrum. The amplitude of absorptive peaks and the corresponding wavelengths represented obvious diurnal variation. In the sunny days,the relative intensities of the sky scattering spectra are convex in the shortwave region. In the cloudy and haze days, the sky scattering spectra are convex in the long wave region. These results correspond to the light scattering theory. Then the appropriate reference spectrums were selected according to the SO2 and O3 column concentration provided by OMI (Ozone Monitoring Instrument) and the absorption cross section obtained from HITRAN (High-resolution transmission molecular absorption database) database. At last, the column concentrations of SO2 and O3 at another moment were retrieved based on differential optical absorption spectroscopy(DOAS) and least square method. The results revealed that the column concentrations of SO2 and O3 calculated in this method were comparable to the data from OMI. Therefore, the missing SO2 and O3 column concentrations data resulting from spatio-temporal resolution could be estimated and this method can make a complement to OMI satellite data.