AIRBORNE CO2 COHERENT LIDAR FOR MEASUREMENTS OF ATMOSPHERIC AEROSOL AND CLOUD BACKSCATTER

An airborne CO2 coherent lidar has been developed and flown on over 30 flights of the NASA DC-8 research aircraft to obtain aerosol and cloud backscatter and extinction data at a wavelength near 9 mum. Designed to operate in either zenith- or nadir-directed modes, the lidar can be used to measure vertical profiles of backscatter throughout the vertical extent of the troposphere and the lower stratosphere. Backscatter measurements in absolute units are obtained through a hard-target calibration methodology. The use of coherent detection results in high sensitivity and narrow field of view, the latter property greatly reducing multiple-scattering effects. Aerosol backscatter profile intercomparisons with other airborne and ground-based CO2 lidars were conducted during instrument checkout flights over the NASA Ames Research Center before extended deployment over the Pacific Ocean. Selected results from data taken during the flights over the Pacific Ocean are presented, emphasizing intercomparisons with backscatter profile data obtained at 1.06 mum with a NASA Goddard Space Flight Center Nd:YAG lidar on the same flights.