Scopes and Challenges of Dual-Doppler Lidar Wind Measurements - An Error Analysis

Doppler Lidars are state-of-the-art measurement systems, which are widely used to investigate atmospheric turbulence. In recent years, Dual-Doppler measurements have become increasingly important, since they allow for accurate measurements of two windfield components with high time and spatial resolution, which led to applications in surface layer turbulent structure investigation (Newsom, 2008, Boundary-Layer Meteorol.) and boundary layer turbulence (Calhoun, 2006, J. Appl. Meteor. Climatol.). However, only few publications are concerned with Dual-Doppler errors (Davies, 2005, J. Opt. A: Pure Appl. Opt.), and none has covered errors of coplanar scans. The KIT Dual-Doppler Lidar system consists of two LMCT `WindTracers' and is operated by the Institute for Meteorology and Climate research at Karlsruhe Institute of Technology. With this worldwide unique setup of two simulatenously controlled Doppler Lidars, an in-depth study concerning all aspects of Dual-Doppler Lidar errors was accomplished. The analysis covers single lidar errors, their propagation to Dual-Doppler results, and general errors in Dual-Doppler applications, ranging from time synchronization and resolution errors to beam displacement and retrieval algorithm errors. The results allow users to accurately estimate their measurement errors, and enable them to optimize their scan patterns and lidar configurations with respect to desired accuracy and atmospheric conditions.