Airborne Doppler wind LIDAR technology demonstration for Aeolus: from pre-launch campaigns to mission performance validation

Kurzfassung

In cooperation with the European Space Agency (ESA) and Airbus Defense and Space (DS), the German Aerospace Center (DLR) developed the ALADIN Airborne Demonstrator (A2D). Also operating at 355 nm wavelength, it is the prototype of the first direct-detection Doppler wind lidar instrument in space - ALADIN (Atmospheric Laser Doppler Instrument) - the single payload of ESA’s Aeolus mission. The A2D was deployed for extensive ground-based measurements and airborne campaigns in the years of mission preparation, with the goal to test operational procedures and refine the algorithms for the processing chain. Experience gained with the A2D supported the ground tests conducted with ALADIN before the launch of Aeolus in 2018. It also laid the foundation for the continuous performance monitoring of the mission, performed within the Data Innovation and Science Cluster (DISC), led by DLR. After launch, DLR executed four airborne campaigns with a focus on validating the Aeolus wind products during different phases of the mission and in diverse geographical and meteorological conditions. During these campaigns, the DLR Falcon aircraft was equipped with the A2D and a high-accuracy scanning heterodyne-detection 2-µm Doppler wind lidar (DWL), used as a reference. Complementary and synergistic results from both DWLs do not only allow for the characterization of the Aeolus and A2D wind errors, but also provide recommendations for the optimization of the Aeolus wind retrieval. Fielding the A2D as a test-bed and validation tool for the Aeolus mission has been a milestone for space lidars and vital for the success of Aeolus, as it has been providing efficient access to instrument specifics in the technological, analytical and scientific domains. The paper covers selected aspects of the airborne technology demonstration program that has supported Aeolus in becoming a successful explorer mission, able to provide high impact data for numerical weather prediction institutions around the world on an operational basis.