The Aeolus mission by ESA was operational from August 2018 to July 2023. Aeolus carried the direct-detection Atmospheric LAser Doppler INstrument (ALADIN). To support Aeolus, the ALADIN Airborne Demonstrator (A2D) was developed. Both ALADIN and A2D consist of so-called Rayleigh and Mie channels to measure wind from molecular and particulate backscatter signals, respectively. The Mie channel relies on determining the spatial location of a fringe being imaged on the detector. The accuracy of the retrieved winds depends on the analytic algorithm used for determining the fringe location. In this paper, the performance of two non-linear fit-based algorithms is investigated by applying them to airborne A2D data. For performance validation, the data of a heterodyne-detection wind lidar are used as a reference. In addition, a fast and non-fit-based algorithm relying on a four-pixel intensity ratio approach (R4) has been developed and yielded similar accuracy, but at a much faster computation time.
Witschas et al. (Thu,) studied this question.