TECIS-1 Cloud and Aerosol Detection Method and Comparison

The Terrestrial Ecosystem Carbon Inventory Satellite (TECIS-1) is a Chinese-developed satellite that employs both active and passive remote sensing technologies for forest carbon monitoring. Equipped with a multi-beam lidar system comprising a laser altimeter and a dedicated atmospheric lidar channel, TECIS-1 supports critical applications in forest vegetation classification and the mapping of cloud and aerosol distributions. In this study, we propose a complete workflow for cloud-aerosol detection and parameter retrieval using 532 nm and 1064 nm attenuated backscatter data from TECIS-1 Level 1B products, combined with GMAO MERRA-2 reanalysis data. The color ratio, depolarization ratio and prior statistical information are incorporated to classify the cloud and aerosol layers. Then the cloud-top height (CTH) and aerosol optical depth (AOD) are derived from the geometry of cloud layers and aerosol extinction profiles. The retrieval results from the study area, encompassing northern/central China and the western North Pacific, are compared with MODIS cloud products and MODIS AOD data, Quantitative evaluations indicate that, based on 394 samples across six tracks from latitudes 10° to 75°N in 2023, TECIS-1’s CTH measurements were consistent with those from MODIS, with a root mean square difference (RMSD) of 2.13 km for single-layer opaque clouds and 2.42 km for single-layer optically thin clouds. The AOD comparison area is located in a region of northern China prone to dust storms. When compared with MODIS products, the overall root mean square difference (RMSD) of the retrieved AOD was 0.278. These results indicate that TECIS-1 can be used for cloud and aerosol detection, and provide a methodological reference for data processing and application of Chinese spaceborne atmospheric lidar systems.