Investigating the Performance of Aeolus L2A Products Over Europe with Earlinet Ground-Based Lidars

In this study, we present a comparison of the AEOLUS satellite L2A aerosol product with the retrievals of the ground-based lidar systems of EARLINET (European Aerosol Research Lidar Network), part the European Research Infrastructure for the observation of Aerosol, Clouds and Trace Gases (ACTRIS). Dedicated ground-based measurements during AEOLUS overpasses have been performed among the 18 member stations since the beginning of the mission. The satellite timeseries covers the period 06/2019 – 05/2023, including observations processed with Baseline 15 and 16. In order to identify a collocation, the satellite must pass closer than 120 km around a station and also within a time interval of ±1.5 hours from the lidar measurement time. The AEOLUS backscatter and extinction coefficient profiles at 355nm are compared with the corresponding ground-based profiles. Biases are calculated in different atmospheric regions and the correlation of the two timeseries is also investigated. The ground-based dataset is split in two categories, measurements that include the particle linear depolarization ratio (PLDR) profile at 355nm and measurements that do not. PLDR allows us to calculate profile of the co-polar backscatter component that is directly comparable with AEOLUS. The total backscatter coefficient is used when the PLDR is not available. The main aspects of this analysis involve both searching for random and systematic bias patterns in the AEOLUS timeseries and investigating their link to other relevant parameters such as the aerosol load and the Baseline version.