Airborne Wind Lidar Observations for the Calibration and Validation of ESA's Wind Mission Aeolus

Kurzfassung

Since the successful launch of ESA's Earth Explorer mission Aeolus in August 2018, atmospheric wind profiles from the ground to the lower stratosphere are being acquired on a global scale deploying the first-ever satellite-borne wind lidar system ALADIN (Atmospheric LAser Doppler INstrument). ALADIN provides one component of the wind vector along the instrument's line-of-sight (LOS) with a vertical resolution of 0.25 km to 2 km depending on altitude, while the precision in wind speed is between 2 m/s to 4 m/s. The near-real-time wind observations contribute to improving the accuracy of numerical weather prediction and advance the understanding of tropical dynamics and processes relevant to climate variability. Already several years before the satellite launch, an airborne prototype of the Aeolus payload, the ALADIN Airborne Demonstrator (A2D), was developed at DLR (German Aerospace Center). Due to its representative design and operating principle, the A2D has since delivered valuable information on the wind measurement strategies of the satellite instrument as well as on the optimization of the wind retrieval and related quality-control algorithms. Broad vertical and horizontal coverage across the troposphere is achieved thanks to the complementary design of the A2D receiver, which, like ALADIN, comprises a Rayleigh and Mie channel for analysing both molecular and particulate backscatter signals. In addition to the A2D, DLR's research aircraft carries a well-established coherent Doppler wind lidar (2-µm DWL) which allows determining the wind vector with accuracy of better than 0.1 m/s and precision of better than 1 m/s. Hence, both instruments represent key instruments for the calibration and validation activities during the Aeolus mission.