Lidar measurements taken with a large aperture liquid mirror. 2. Sodium resonance-fluorescence system

Sodium resonance-fluorescence Lidar is an established technique for measuri ng atmospheric composition and dynamics in the mesopause region. A large-po wer-aperture product (6.6-W m(2)) sodium resonance-fluorescence lidar has b een built as a part of the Purple Crow Lidar (PCL) at The University of Wes tern Ontario. This sodium resonance-fluorescence lidar measures, with high optical efficiency, both sodium density and temperature profiles in the 83- 100-km region. The sodium lidar operates simultaneously with a powerful Ray leigh- and Raman-scatter lidar (66 W m(2)). The PCL is thus capable of simu ltaneous measurement of temperature from the tropopause to the lower thermo sphere. The sodium resonance-fluorescence lidar is shown to be able to meas ure temperature to an absolute precision of 1.5 K and a statistical accurac y of 1 K with a spatial-temporal resolution of 72 (km s) at an altitude of 92 km. We present results from three nights of measurements taken with the sodium lidar and compare these with coincident Rayleigh-scatter lidar measu rements. These measurements show significant differences between the temper ature profiles derived by the two techniques, which we attribute to variati ons in the ratio of molecular nitrogen to molecular oxygen that are not acc ounted for in the standard Rayleigh-scatter temperature analysis. (C) 2000 Optical Society of America OCIS codes: 010.0010, 010.3640.