Investigation of Turbulent Processes in the Lower Troposphere with Water Vapor DIAL and Radar–RASS

Abstract

High-resolution water vapor and wind measurements in the lower troposphere within the scope of the Baltic Sea Experiment (BALTEX) are presented. The measurements were performed during a field campaign with a new water vapor differential absorption lidar (DIAL) system and a radar?radio acoustic sounding system (radar?RASS). The analysis of a continuous 24-h measurement period shows that the resolution and the accuracy of these instruments are capable of measuring profiles of water vapor and vertical wind fluctuation moments up to the second order to investigate turbulent processes in the convective boundary layer. Besides the high-resolution data obtained with each instrument it is their combination that yields a further important variable in the boundary layer: the turbulent latent heat flux measured directly using the eddy correlation method. The results demonstrate that active remote sensing instruments like DIAL and radar?RASS can be routinely applied to provide previously unavailable datasets for detailed investigations of turbulent processes. Thus, the instruments can contribute significantly to one of the major goals of regional continental-scale experiments like BALTEX: the investigation of models and the improvement of their parameterization of small-scale processes.