Retrieving Optical Depths and Lidar Ratios for Transparent Layers Above Opaque Water Clouds From CALIPSO Lidar Measurements

For measurements that are made by the CALIPSO lidar, the layer-integrated attenuated backscatter of opaque water clouds gamma' water,O can be accurately estimated for those cases for which there is no overlying aerosol or cloud layer. When transparent overlying layers of clouds or aerosols are present, the layer-integrated attenuated backscatter that is measured for the water cloud is reduced by a factor that is equal to the two-way transmittance of the upper layer. Because the layer-integrated depolarization ratio can be used to obtain an independent estimate of gamma' water,O , we can subsequently derive both the optical depth and an estimate of the layer-averaged lidar ratio of the overlying layer.