Raman lidar profiling of atmospheric water vapor

The authors describe two Raman lidar systems that they are developing for the measurement of atmospheric humidity. One, which has been under development for several years, is used for their own studies at Sandia. The Sandia lidar system is housed in two mobile semitrailers, one trailer serving as a mobile laboratory and the other as a support vehicle providing a data acquisition/analysis area. The lidar uses an injection-seeded excimer laser to provide a beam with reduced divergence and spectral bandwidth, operated at 308 nm during both nighttime and daytime. Enhanced dynamic range, for daytime operation in particular, is provided by using photon counting in the narrow field-of-view channel, and analog to digital conversion in the wide field-of-view channel. The second Raman lidar system under development will have a permanent residence at the Department of Energy´s ARM (Atmospheric Radiation Measurement program) CART (Cloud and Radiation Testbed) site near Lament, Oklahoma. This system is based on a high-power 355-nm laser beam produced by a frequency-tripled Nd:YAG laser