Doppler wind lidar

Doppler wind lidar retrieves atmospheric wind speed profiles by measuring the frequency shift imparted by moving scatterers on laser light backscattered from aerosol particles and air molecules. Two detection architectures are used: direct-detection systems resolve the Doppler shift spectrally using a high-resolution interferometer, while coherent systems mix the return with a local oscillator reference. Both architectures deliver line-of-sight wind components that are projected to horizontal wind profiles through instrument geometry.

ESA's Aeolus satellite, carrying the ALADIN instrument, operated as a spaceborne Doppler wind lidar from August 2018 to July 2023.^[1] ALADIN operates at 355 nm UV with two spectrometers in parallel: a Fizeau interferometer on the Mie channel for aerosol-laden layers, and a dual-filter Fabry-Perot on the Rayleigh channel for clear-air molecular signal. Pulse energy is approximately 80 mJ. The instrument points 35 degrees off nadir, perpendicular to the orbital track, sampling 24 altitude layers from the surface to 30 km.^[2][3] Assimilation experiments at ECMWF demonstrated measurable positive impact on numerical weather prediction skill, particularly in the tropics and the southern hemisphere where radiosonde coverage is sparse.^[4]

Core data products are profiles of the horizontal line-of-sight wind component, serving NWP assimilation, climate reanalysis, and validation of general circulation model wind fields.