The need to measure the background wind in the height range 25 - 60 km, where there was no possibility to monitor adequately the wind field, led to the development of a new Doppler lidar designed to cover this altitude range and, therefore, it had to rely on Rayleigh scattering. The light source is a pulsed monomode doubled Nd:YAG laser (532 nm). The Doppler shift of the backscattered echo is measured by inter-comparing the signal detected through each of the two band-passes of a single dual high-resolution Fabry Perot interferometer tuned on either side of the backscattered line. Wind profiles extending up to about 45 km have been obtained with a preliminary device for typically 2 - 3 hours integration time and 2 km height resolution. The wind profiles were originally limited downwards to altitudes where the contribution of the Mie scattering by aerosols can be neglected. The possibility to adapt the instrument for wind measurements in regions where the Mie scattering becomes important has been recently theoretically and experimentally demonstrated.
展开▼
