LIDAR CALIBRATION EXPERIMENTS

A series of atmospheric aerosol diffusion experiments combined with li dar detection was conducted to evaluate and calibrate an existing retr ieval algorithm for aerosol backscatter lidar systems. The calibration experiments made use of two (almost) identical mini-lidar systems for aerosol cloud detection to test the reproducibility and uncertainty o f lidars. Lidar data were obtained from both single-ended and double-e nded Lidar configurations. A backstop was introduced in one of the exp eriments and a new method was developed where information obtained fro m the backstop can be used in the inversion algorithm. Independent in- situ aerosol plume concentrations were obtained from a simultaneous tr acer gas experiment with SF6, and comparisons with the two lidars were made. The study shows that the reproducibility of the lidars is withi n 15%, including measurements from both sides of a plume. The correspo ndence with in-situ measurements is excellent. Finally, the new backst op method is able to reveal information which can close the lidar equa tion by obtaining the relation between backscatter and extinction in a n aerosol cloud.