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. Aeolus, launched on 22 August in 2018, is thefirst ever satellite to directly observe wind information from the surfaceup to 30 km on a global scale. An airborne prototype instrument called ALADIN airbornedemonstrator (A2D) was developed at the German Aerospace Center (DLR) forvalidating the Aeolus measurement principle based on realistic atmosphericsignals. To obtain accurate wind retrievals, the A2D uses a measuredRayleigh response calibration (MRRC) to calibrate its Rayleigh channelsignals. However, differences exist between the respective atmospherictemperature profiles that are present during the conduction of the MRRC andthe actual wind measurements. These differences are an important source ofwind bias since the atmospheric temperature has a direct effect on theinstrument response calibration. Furthermore, some experimental limitationsand requirements need to be considered carefully to achieve a reliable MRRC.The atmospheric and instrumental variability thus currently limit thereliability and repeatability of a MRRC. In this paper, a procedure for asimulated Rayleigh response calibration (SRRC) is developed and presented inorder to resolve these limitations of the A2D MRRC. At first thetransmission functions of the A2D Rayleigh channel double-edge Fabry–Perotinterferometers (FPIs) in the internal reference path and the atmosphericpath are characterized and optimized based on measurements performed duringdifferent airborne and ground-based campaigns. The optimized FPItransmission functions are then combined with the laser reference spectrumand the temperature-dependent molecular Rayleigh backscatter spectrum toderive an accurate A2D SRRC which can finally be implemented into the windretrieval. Using dropsonde data as a reference, a statistical analysis basedon a dataset from a flight campaign in 2016 reveals a bias and a standarddeviation of line-of-sight (LOS) wind speeds derived from a SRRC of only0.05 and 2.52 m s −1 , respectively. Compared to the resultderived from a MRRC with a bias of 0.23 m s −1 and a standard deviationof 2.20 m s −1 , the accuracy improved and the precision is consideredto be at the same level. Furthermore, it is shown that the SRRC allows for thesimulation of receiver responses over the whole altitude range from theaircraft down to sea level, thus overcoming limitations due to high groundelevation during the acquisition of an airborne instrument responsecalibration.

Rayleigh wind retrieval for the ALADIN airborne demonstrator of the Aeolus mission using simulated response calibration