Lidar depolarization from multiple scattering in marine stratus clouds

The generation of ruby lidar depolarization from multiple scattering in marine stratus clouds has been examined systematically from a field site on the southern California coast. Investigated were the effects on the linear depolarization ratio delta of lidar receiver field of view (FOV), elevation angle, and laser alignment error. An approximately linear increase in maximum delta values was observed with increasing receiver FOV, and the importance of accurate transmitter/receiver alignment has been demonstrated. An elevation angle dependence to the delta values was observed as a consequence of the vertical inhomogeneity of water cloud content above cloud base. Time histories of the depolarization characteristics of dissipating stratus clouds revealed significant variability in delta values due to cloud composition variations. Employing a 1-mrad transmitter FOV, maximum delta values of 0.21 and 0.33 were observed with 1and 3-mrad receiver FOVs, respectively.