Iterative method for determining boundaries and lidar ratio of permeable layer of a space lidar

Space lidar is a unique tool for detecting the 3D properties of cloud and aerosol layers. Layer boundaries and lidar ratio are significant preconditions for retrieving the layer optical properties of a space lidar. The CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) team adopts the threshold method to accurately detect a layer top. However, the layer base detection continues to rely on the slope method, which causes considerable uncertainty. Furthermore, a fixed lidar ratio is mainly used for retrieving optical properties of layers of the same layer type, which also contains large uncertainty. To reduce the above uncertainties, we propose an iterative method to determine layer base and lidar ratio of a permeable layer of a space lidar on the basis of lidar ratio and transmission relationship. The simulated and measured experimental results demonstrate that the proposed iterative method simultaneously retrieves layer boundaries and lidar ratio accurately. The proposed iterative method has the potential to become a significant part of data retrieval of a space lidar in the future.