AOD Derivation from SDGSAT-1/GLI Dataset in Mega-City Area

Aerosol optical depth (AOD) is the key parameter for determining the aerosol radiative effects and air quality variation. It is important to quantify nighttime aerosols using satellite-based night light images to understand their diurnal variations. This study selected high-resolution low light images from the Glimmer Imager (GLI) aboard the SDGSAT-1 satellite to examine spatial-temporal changes in night light emitted from the urban surface of Beijing. The radiance observed by SDGSAT-1/GLI was used to discern the AOD changes using the radiance background method (RB) and standard deviation method (SD) based on the characterization of the radiance from artificial light sources. Cloud cleaning processes were conducted to reduce the influence of the cloud cover in the glimmer images of the derived AOD. The results showed that there are good consistencies between the derived AOD results from the remote sensing and nighttime site observations. The radiance background method is better than the standard deviation method for deriving AOD using SDGSAT-1/GLI with the RMSE of its RB (0.0984) being greater than that of the SD (0.7653). The influence of moonlight, atmospheric absorption, and positioning errors on the results is briefly discussed. This paper shows that SDGSAT-1 can obtain relatively reliable night AOD values based on our investigations using the available satellite images taken in winter and spring, and that it has the potential to provide the scientific products of nighttime AOD.

Automated summary

This study used high-resolution low light images from the GLI instrument on board the SDGSAT-1 satellite to investigate the spatial-temporal changes in night light emitted from the urban surface of Beijing. The results showed good consistencies between the derived aerosol optical depth (AOD) from remote sensing and nighttime site observations. The radiance background method (RB) was found to be better than the standard deviation method (SD) for deriving AOD using the SDGSAT-1/GLI with a lower root mean square error (RMSE) of 0.0984 compared to 0.7653 for SD. This study demonstrates that SDGSAT-1 can provide relatively reliable night AOD values and has the potential to deliver scientific products of nighttime AOD.