Column-Weighted Carbon Dioxide Concentration Under the Cloud Retrieved by Spaceborne IPDA Lidar

In 2022, China launched the world’s first satellite for active lidar CO2 detection, the Atmospheric Environmental Monitoring Satellite (AEMS, or DQ-1). Its key payload, the Aerosol and Carbon Detection LiDAR (ACDL), provides high-precision CO2 column concentration (XCO2) measurements. The system can treat optically thick clouds as hard targets while penetrating thin clouds, enabling separation of above-cloud and whole-column CO2 signals for below-cloud XCO2 retrievals. XCO2 retrievals under the cloud better represent near-surface CO2 concentrations.