DLR Airborne Campaigns and Results

Kurzfassung

During the first three years of ESA’s wind lidar mission the German Aerospace Center (DLR) conducted four airborne campaigns with a focus on validating the Aeolus wind products during different states of the ESA mission since launch in 2018. After two campaigns in Europe and one in Iceland, finally the AVATAR-T (Aeolus VAlidation Through Airborne LidaRs in the Tropics) campaign was performed around the Cabo Verde archipelago in September 2021 as part of the Joint Aeolus Tropical Atlantic Campaign (JATAC). During these campaigns, the DLR Falcon aircraft was equipped with two Doppler wind lidar instruments (DWLs): the ALADIN Airborne Demonstrator (A2D), representing a prototype of the direct-detection DWL on-board Aeolus with a high degree of commonality in terms of design and measurement principle, and a high-accuracy scanning heterodyne detection 2-µm DWL, used as a reference. The two instruments were operated in parallel in a downward looking configuration for coordinated flights along a total distance of 26,000 km under the Aeolus measurement track. Complementary and synergistic results from both DWLs allowed us to characterize the Aeolus systematic and random wind errors evolutions and to provide recommendations for the optimization of the Aeolus wind retrieval. After having studied the influence of different QC schemes on the validation results, a two-step QC approach was developed that ensures effective outlier removal, which is important for both Mie and Rayleigh winds. This approach improves the comparability of validation studies from different teams and provides results in compliance with the Aeolus mission requirements. In addition, the A2D Mie wind retrieval has been further refined to obtain more valid results. This is currently studied to potentially also increase the Aeolus Mie wind data coverage and accuracy together with the Aeolus-DISC. This contribution gives an overview of the airborne validation campaigns, related results and the status of the ongoing analysis w.r.t. inter-campaign comparison of the Aeolus performance and algorithm developments.