Abstract: NO2 slant column density is retrieved using eight discrete wavelengths (DW) combined with differential optical absorption spectroscopy (DOAS) technique, and the difference between DW-DOAS and the traditional DOAS technique using continuous wavelengths is compared and discussed. The feasibility of DW-DOAS is validated using the ground-based data and the satellite-based data from environmental trace gases monitoring instrument (EMI) in the study. The results show that compared with the traditional DOAS, the average errors of the two data retrieved using DW-DOAS are both less than 7%, and the correlations are above 0.9, proving that the DW-DOAS retrieve method has certain application value in retrieving trace gas column density. In addition, it is also shown that the DW-DOAS algorithm can quickly and efficiently retrieve the NO2 slant column density only using a small amount of spectral information. This work not only provides a basis for further research on subsequent algorithms, but also indicates that based on DW-DOAS algorithm, simpler and more efficient instruments can be designed for monitoring NO2 with high spatial and temporal resolution.

Key words: differential optical absorption spectroscopy, discrete wavelength, NO2 slant column density; environmental trace gases monitoring instrument