Remote sensing of NO using a differential absorption lidar.

Single-ended remote sensing measurements of atmospheric NO have been made using differential absorption of frequency-doubled pulsed CO(2) laser radiation backscattered from topographic targets. Returns were obtained from targets at ranges out to 1.4 km, and significant NO concentrations above ambient were observed over a path which crossed a traffic roadway at a range of 0.5 km. In view of the severe atmospheric water vapor absorption in the spectral region containing the NO absorption band, the range dependence of the lidar returns was also measured in order to determine the differential absorption of the ambient atmosphere.The results differed significantly from those computed from atmospheric transmission data tapes.