Research on Aerosol Optical Depth Remote Sensing Retrieval Over Urban Areas Using FY-4B Satellite

Fengyun-4B (FY-4B) is the latest generation of Chinese geostationary meteorological satellite, which was launched on 3 June 2021. This paper presents the retrievals of the aerosol optical depth(AOD) for Beijing and its surrounding areas in September-November 2022 were carried out based on AGRI data and MODIS surface reflectance data. Firstly, cloud detection is performed on the AGRI L1 data, and then the MOD09 surface reflectance product is utilized to construct the AGRI blue band monthly surface reflectance library, while the AERONET aerosol product were used to select an aerosol model applicable to the Beijing region. The validation results with AERONET AOD show that the correlation coefficients of the AOD retrievals with AERONET AOD are greater than 0.85, and the root mean square error (RMSE) is less than 0.2, and more than 55% of the data points are within the expected error EE, but the AOD retrievals are slightly higher when the AOD is $\lt0.1$; in terms of the spatial distribution, the AOD retrievals show good agreement with both MODIS DT and DB AOD. The above results demonstrate the potential application of FY-4B AGRI in monitoring daily AOD Variations.