Research of NO2 vertical profiles with look-up table method based on MAX-DOAS

Obtaining the vertical distribution profile of trace gas is of great significance for studying the diffusion procedure of air pollution. In this article, a look-up table method based on multi-axis differential optical absorption spectroscopy (MAX-DOAS) technology is established for retrieving the tropospheric NO₂ vertical distribution profiles. This method retrieves the aerosol extinction profiles with minimum cost function. Then, the aerosol extinction profiles and the atmospheric radiation transfer model (RTM) are employed to establish the look-up table for retrieving the NO₂ vertical column densities (VCDs) and profiles. The measured NO₂ differential slant column densities (DSCDs) are compared with the NO₂ DSCDs simulated by the atmospheric RTM, and the NO₂ VCDs, the weight factor of NO₂ in the boundary layer, and the boundary layer height are obtained by the minimization process. The look-up table is established to retrieve NO₂ VCDs based on MAX-DOAS measurements in Huaibei area, and the results are compared with the data from Copernicus Atmospheric Monitoring Service (CAMS) model. It is found that there are nearly consistent and the correlation coefficient R² is more than 0.86. The results show that this technology provides a more convenient and accurate retrieval method for the stereoscopic monitoring of atmospheric environment.