Remote measurement of gases using differential-absorption lidar

The differential-absorption lidar (DIAL) technique is recognized worldwide as being a sensitive and long-range method for making remote measurements of gases. This article summarizes research performed on the infrared DIAL. A deuterium fluoride lidar was used for the remote measurement of integrated concentrations of HCl, CH4, and N2O in a sample chamber between the lidar and a topographic target. A CO2 lidar was employed for range-resolved measurements of ambient water vapor using radiation backscattered from naturally occurring aerosols. Also, integrated concentrations of ambient ethylene were measured using a CO2 lidar system, and good agreement was obtained between lidar and in situ measured concentrations. Calculations indicate that range-resolved concentration profiles can be obtained for many gases at a range of 10 km using commercially available components.