Radiometric calibration and reflectivity inversion of spaceborne LiDAR

Light detection and ranging (LiDAR) onboard satellites are used not only for global height measurement but also to actively obtain global surface reflectance, which helps in separating surface targets on the basis of their reflectivity properties. In this paper, methods for obtaining surface reflectance with the LiDAR onboard the Terrestrial Ecosystem Carbon Inventory Satellite, which is nicknamed Goumang, are studied. The radiation model for LiDAR to obtain surface reflectance is constructed on the basis of the transmission path of the laser. A method for obtaining the coefficients of the radiometric calibration, which are key parameters for calculating surface reflectance in the radiation model, is designed. These coefficients are derived from automated data collected at the Chinese radiometric calibration site in Dunhuang. The uncertainty of this radiometric calibration is evaluated, yielding a value of approximately 5%. Additionally, a retrieval method for obtaining global surface reflectance based on global aerosol products from other satellites is introduced. The results are compared with ground-measured values, revealing a relative deviation of approximately 10%. This research provides a feasible pathway for retrieving global surface reflectance by LiDAR.