Airborne Lidar Observations Supporting the ADM-Aeolus Mission for Global Wind Profiling
Reitebuch, Oliver; Lemmerz, Christian; Marksteiner, Uwe; Rahm, Stephan; Witschas, Benjamin
The global measurement of wind profiles is considered to be of highest priority regarding the needs for numerical weather prediction (NWP). Therefore, ESA implemented the Atmospheric Dynamics Mission ADM-Aeolus with a scheduled launch date in 2015. ADM-Aeolus will be the first lidar mission to sense the global wind field from space. It will demonstrate the potential of the Doppler wind lidar technology for providing vertical profiles of wind speed up to 20-30 km. The instrument is based on a direct-detection Doppler lidar operating at an ultraviolet wavelength of 354.9 nm with two spectrometers for measuring the Doppler frequency shift from molecules and aerosol/cloud particles.
In order to assess the performance of the Doppler lidar ALADIN on ADM-Aeolus and to optimize the retrieval algorithms with atmospheric signals, an airborne prototype - the ALADIN Airborne Demonstrator A2D - was developed. The A2D was the first airborne direct-detection Doppler lidar with its maiden flight on the DLR Falcon aircraft in 2005. Three airborne campaigns with a coherent-detection 2-μm wind lidar and the direct-detection wind lidar A2D were performed for pre-launch validation of ADM-Aeolus from 2007-2009. The latest airborne campaign was performed in the area of Greenland, Iceland and the North Atlantic in 2009. Comparisons of the wind speed profiles retrieved from both lidar systems allowed the validation of the measurement principle of the satellite and the optimisation of retrieval algorithms.
Measured wind fields from both lidars will be presented along with analyses from the NWP model at ECMWF. For the molecular and the aerosol channel of the prototype instrument, statistical comparisons yielded random errors of less than 2.5 m/s and 1.5 m/s, respectively.