Low and optically thin cloud measurements using a Raman-Mie lidar

We analyze the potential of measuring low-altitude optically thin clouds with a Raman-elastic lidar in the daytime. Optical depths of low clouds are derived by two separate methods from nitrogen Raman and elastic-scattering returns. By correcting for aerosol influences with the combined Raman-elastic returns, Mie retrievals of low-cloud optical depth can be dramatically improved and show good agreement with the direct Raman retrievals. Furthermore, a lidar ratio profile is mapped out and shown to be consistent with realistic water phase cloud models. The variability of lidar ratios allows us to explore the distribution of small droplets near the cloud perimeter. (C) 2009 Optical Society of America