The ADM-Aeolus mission has been designed to provide timely and accurate profiles of the world’s winds along with information on aerosols and clouds to advance our understanding of atmospheric dynamics and to provide information for weather forecasts. To do this, the satellite carries a complex instrument: Aladin, the first wind lidar in space.
A lidar uses the phenomenon of light scattering and the Doppler Effect to acquire data on wind. A lidar works by emitting a short, but powerful, light pulse from a laser through the atmosphere and then collects light that is backscattered from particles of gas and dust and droplets of water in the atmosphere. The time between sending the light pulse and receiving the signal back determines the distance to the ‘scatterers’ and thus the altitude above Earth. As the scattering particles are moving in the wind, the wavelength of the scattered light is shifted by a small about as a function of speed. The Doppler wind lidar measures this change so that the velocity of the wind can be determined.