Aerosol optical depth retrieval over land using MODIS data and its application in monitoring air quality

Atmospheric remote sensing offers us a view to estimate air quality in describing the aerosol distribution either for a local or global coverage because aerosol parameters, such as aerosol optical depth (AOD) are significant indicators of the air quality. However, AOD retrieval over land still remains a difficult task because the measured signal is a composite of reflectance of sunlight by the variable surface covers and back scattering by the semitransparent aerosol layer. In this paper, an approach using bi-angle with Moderate Resolution Imaging Spectroradiometer (MODIS) data was presented. The derived AOD is compared to AERONET observations in the Asia area and a retrieval error within 16% is found. Moreover, a biomass burning episode in North China between June 7, 2007 was presented, it is demonstrated that AOD increased up to 2.0 during the burning phase and then returned to normal values (0.2-0.5), which fully in line with the observation result.