Subtropical cirrus cloud extinction to backscatter ratios measured by Raman Lidar during CAMEX-3

The NASA/GSFC Scanning Raman Lidar was stationed on Andos Island, Bahamas for the third Convection and Moisture Experiment (CAMEX 3) held in August-September, 1998 and acquired an extensive set of cirrus cloud measurements [Whiteman et al., 2001]. Distinct differences in the optical properties of the clouds are found when the cirrus are hurricane-induced versus non-hurricane-induced. Hurricane-induced cirrus clouds are found to generally possess lower values of extinction-to-backscatter ratio (S) than non-hurricane-induced clouds. Comparison of the S measurements made here with those of other studies reveal at times large differences. Given that S is often a required parameter for space-based retrievals of cloud optical depth using backscatter lidar, these large differences in S measurements imply difficulties in developing a parameterization of S for use in space-based lidar retrievals.