Extinction to Backscatter Ratio of Cirrus Clouds Retrieved by Spaceborne Lidar over China

The two-year spaceborne lidar data are used to study the extinction-to-backscatter ratio, i.e., lidar ratio (LR), of cirrus clouds over China. The LRs are retrieved by the combination of the equation between multiply scattering factor and optical depth and the equation between LR and transmittance. Additionally, five data quality control standards have been made to assure the high availability. The mean value of LR is 24 without prominent monthly and seasonal variations. The LRs are relatively high in the intertropical convergence zone over China, and increase with latitude decreasing (approximately from 22 to 27). This demonstrates that constant LR should be changed with latitude in order to enhance the quality of retrieval of cirrus cloud optical depth.