Airborne lidar observations of water vapor transport

Water vapor, a minor constituent of the earth´s atmosphere, plays a major role in the radiation budget and the water cycle with important implications for weather and climate. Due to the heterogeneous distribution of its sources, evaporation, and sinks, condensation and precipitation, and due to the complexity of atmospheric motion and mixing, its distribution is highly variable. Despite the relevance of this trace gas, its variability and instrumental shortcomings impede accurate measurements of its concentration. Advanced airborne lidar instruments aid to better observe water vapor and its transport in the atmosphere, in view of an improved understanding of the related key implications. The combination of a water vapor differential absorption lidar and a heterodyne detection Doppler wind lidar on an aircraft allows to measure vertical profiles of the latent heat flux in a convective boundary layer and to portray the small-to meso-scale humidity transport and variability beneath the aircraft with high accuracy and spatial resolution, in the frame of dedicated meteorological process studies.