Detector performance of the space-borne Doppler wind lidar aboard the Aeolus satellite

Kurzfassung

The Aeolus mission, launched by the European Space Agency (ESA) in August 2018, marked a significant milestone in Earth observation by providing global wind profiles in near-real time using the first Doppler wind lidar in space: The Atmospheric Laser Doppler Instrument (ALADIN). Aeolus exceeded its planned three-year lifetime, providing invaluable data for weather prediction and scientific research until its conclusion in July 2023. A key challenge throughout the mission was mitigating the impact of hot pixels on the ALADIN charge-coupled device (CCD) detectors which affected the wind data quality. These dark current anomalies manifested as random telegraph signals and sporadic shifts in the median dark current levels, necessitating the development of a specialized calibration technique to minimize systematic wind errors. Regular dark current calibrations, conducted up to eight times per day, yielded a comprehensive dataset used to categorize hot pixels and derive statistical parameters critical for reprocessing Aeolus data products. Following the end of the operational mission in April 2023, a series of specialized in-orbit tests, referred to as end-of-life (EOL) activities, provided valuable insights into the temperature dependence of dark currents on the ALADIN detectors, shedding light on potential root causes of the hot pixels. The findings are relevant for the space lidar missions EarthCARE and Aeolus-2, as well as for other satellite missions using CCD detectors.