ACDL (Aerosol and Carbon Detection Lidar)

ACDL (Aerosol and Carbon Detection Lidar) is a spaceborne multi-function lidar developed by the Shanghai Institute of Optics and Fine Mechanics (SIOM) and integrated by the Shanghai Academy of Spaceflight Technology (SAST) under the China National Space Administration (CNSA). The instrument operates three wavelength channels: 532 nm in high-spectral-resolution lidar (HSRL) mode for aerosol and cloud backscatter profiling, 1064 nm in elastic backscatter mode, and 1572 nm in integrated-path differential absorption (IPDA) mode for atmospheric carbon dioxide column retrieval.^[1][2]

The full instrument name appears as both "Aerosol and Carbon Detection Lidar" ^[1] and "Aerosol and Carbon dioxide Detection Lidar" ^[2]; the WMO OSCAR instrument record uses the former form.

ACDL was first flown on Daqi-1 (DQ-1), China's first dedicated atmospheric composition monitoring satellite. Launch is reported as 15 April 2022 ^[3] and as 16 April 2022 ^[4]. An ACDL unit also flies on Daqi-2 (DQ-2), launched in 2026; payload configuration details for the DQ-2 unit are not described in publicly released documentation as of 2026-06-04.^[3]

The HSRL technique separates molecular from aerosol backscatter signals spectrally, enabling aerosol extinction and backscatter coefficient retrieval without assumptions about the aerosol lidar ratio. The IPDA channel retrieves the column-averaged dry-air mole fraction of CO2 (XCO2) by comparing absorbed and reference signal paths at 1572 nm along the two-way atmospheric path.^[4]