Evaluation of the NCAR-MSU Eye-Safe Differential Absorption Lidar (DIAL) for Continuous Water Vapor Profiling in the Lower Troposphere

Enhanced, high-resolution, accurate and continuous measurements of water vapor are a long-standing observational challenge to the meteorological and climate research and forecasting communities. In an effort to obtain continuous water vapor and aerosol profiles in the lower troposphere, an eye-safe, diode-laser-based, micro-pulse differential absorption lidar (DIAL) instrument has been developed by Montana State University and NCAR's Earth Observing Laboratory. This technology potentially fills a national long-term observing facility gap. After multiple field tests in 2012, several engineering upgrades were identified to make the DIAL useful for the atmospheric sciences community. These upgrades have been accomplished to achieve observations i) closer to the surface and ii) in the presence of clouds and iii) during daytime and iv) to improve the DIAL's stability and reliability. Intercomparison studies were performed in July 2014 in Colorado during the FRAPPE (Front Range Air Pollution and Photochemistry Experiment) field campaign. Substantially improved instrument reliability, uncertainty, systematic biases, detection height statistics and environmental complications will be presented.