Measurements of cirrus cloud backscatter color ratio with a two-wavelength lidar

We present observations of cirrus clouds from June 2006 to July 2007 performed by using a two-wavelength lidar located at Hampton University. For this time period, cirrus clouds were observed mostly in 7-13.5 km altitudes. Data analyses have been performed focusing on a color-ratio retrieval. In total, 86,369 samples from 1,689 profiles (1 min average and 15 m range resolution) containing cirrus clouds with attenuated backscatter ratio (ratio of attenuated total backscatter to the molecular backscatter) larger than 10 have been selected. The cirrus color ratio distribution shows a peak value at about 0.88 and a full width at half-maximum of 0.12.