Abstract

The object of this investigation was to determine if it is feasible to measure cloud droplet size distributions using multiwavelength, ground-based lidars. We chose to measure first the most simple clouds, Altocumulus lenticularis, since in their laminar form they are often characterized by nearly monodisperse droplet distributions. Available for the investigation were doubled ruby and ruby, and carbon dioxide lidars with wavelengths of 0.347, 0.694, and 10.59 µm, respectively, covering well the droplet size ranges expected in the clouds. All the lidars are calibrated absolutely, so that the backscatter coefficient in units of (l/m)(l/sr) is determined. Most of the measurements made to date produce a mathematical inversion that shows a single-mode size distribution with a peak at ~4-µm droplet radius. Clouds that are more laminar in appearance show a sharper peak; clouds that appear more chaotic show a nearly flat distribution between radii of 1 and 9 µm.

© 1985 Optical Society of America