Sodium Resonance Fluorescence Lidar Applications in Atmospheric Science and Astronomy

The mesospheric Na layer is generally confined to the region between 80 and 110 km with a peak near the mesopause where the density ranges from about 103-104 cm-3. The first lidar measurements of the layer were made in the late 1960s following the invention of the tunable dye laser. Numerous groundbased and airborne lidar observations have been conducted during the past 20 years and recently, several spaceborne systems have been proposed. The layer is an excellent tracer of wave motions, and Na lidar studies are now making important contributions to our understanding of the dynamic effects of atmospheric tides and gravity waves near the mesopause. In the field of astronomy, Na lidar techniques are also being developed for creating artificial guide stars that can be used with groundbased adaptive telescopes to compensate image distortion caused by atmospheric turbulence. In this paper the design of modern Na resonance fluorescence lidars is described and applications in atmospheric sciences and astronomy are discussed.