Aerosol measurements in the tropo- and stratosphere by spectral splitting of Rayleigh and Mie signals within a compact lidar of 1 m3

Abstract

Doppler lidars with daylight capability are challenging systems because of the small field of view (FOV), spectral filtering, and other additional subsystems required compared to observations at night. A universal Doppler lidar platform with all the required technologies for automatic operation is assembled. By combining a novel narrow-bandwidth pulsed laser (FWHM ~3 MHz) and a matched interferometer (FWHM ~7.5 MHz) the backscattered signals from molecules and aerosols are separated into two channels within the receiver. By tuning the frequency of the pulsed laser from pulse to pulse with sub-MHz accuracy relative to the interferometer, Doppler-aerosol measurements with largely reduced Rayleigh-signal allow aerosol measurements from ground to ~25 km altitude, including Doppler-wind measurements from the Doppler-shift. The compact lidar (1m 3 ) is built for automatic 24/7 operation and comprises a novel diodepumped alexandrite ring-laser, a 50 cm-telescope and a receiver for solar background free aerosol measurements. The combination of cost-efficient design and fast assembling of such a system allows the construction of a Doppler lidar network with identical units. Such a network can address a wide range of horizontal and vertical scales.