Aerosol; GAN; DN values

The current quantitative retrieval of Aerosol Optical Depth (AOD) typically uses Top-of-atmosphere (TOA) reflectance data obtained by radiometric calibration. Errors can be introduced during the conversion of DN values to TOA reflectance, affecting the retrieval of AOD. Especially when the surface reflectance is relatively high, the conversion error will bring significant errors to the AOD retrieval, as in such cases, the contribution of aerosols to the radiation received by satellite sensors is relatively small.