Study on the retrieval of MODIS 1- km aerosol optical thickness combining extended dark object method and V5.2 algorithm over Beijing

Atmospheric aerosol plays a significant role in radiative budget, climate change, hydrological processes, and the global carbon, nitrogen and sulfur cycles. Aerosol optical thickness (AOT) is a key property used in the characterization of atmospheric aerosol. There is a relatively long history of the quantitative estimation of AOT from remotely sensed imagery; especially the dark object method has already made many progresses in the retrieval of AOT over the areas with low surface reflectance. Based on the analysis of the advantages and limits of dark object method, extended dark object method, V5.2 algorithm and four-branched decision method, we introduce a combined method to retrieve AOT over some areas around Beijing using moderate resolution imaging spectroradiometer (MODIS) data, the retrieval results are validated with AERONET data in Beijing and Xianghe sites.