Relationship Between Backscatter Coefficient and Wavelength of Strong Cirrus Cloud Based on a Three-Wavelength Lidar Measurements

The global occurrence of cirrus clouds could reach as high as 30%, which would modulate the balance of radiation budget between the earth and its atmosphere. For strong cirrus cloud (the attenuated backscatter ratio is greater than 20 at 532 nm wavelength), this research proposes an inversion method by using the color ratio of attenuated backscatter coefficient to estimate the color ratio of backscatter coefficient and analyzes its retrieval errors. Based on the measured strong cirrus cloud data over Hefei west suburb using a three-wavelength Lidar (1 064 nm, 532 nm and 355 nm), three statistical backscatter color ratios of strong cirrus cloud were computed, and the backscatter wavelength index of strong cirrus cloud were estimated. The results indicate that the backscatter wavelength index of strong cirrus cloud is no longer a constant as preconception but a variable quantity relative to the wavelength.