High-Resolution Lidar System for Measuring the Spatial and Temporal Structure of the Mesospheric Sodium Layer
One of the first remote sensing applications of tunable dye lasers was in the study of mesospheric sodium. The layer, which is believed to be of meteoric origin, is confined to altitudes between approximately 80 and 100 km. The layer has been investigated using a variety of techniques since its discovery in the late 1930s. A review of early measurements and the theory of sodium layer chemistry is contained in Brown (1973). Before dye laser based lidar systems were developed, sodium measurements were largely restricted to studying resonantly scattered sunlight. Ground-based measurements of this type were able to define seasonal variations in column abundance, but the sharp layer boundaries were not revealed until rocket-borne dayglow measurements were made (Hunten and Wallace, 196 7). Lidar observations of the vertical structure of the sodium layer were first made in England (Bowman et al., 1969). Since then, similar measurements have been reported from a variety of locations including France (Blamont et al., 1972), Brazil (Kirchoff and Clemesha, 1973), California (Hake et al., 1972), Illinois (Rowlett et al., 1978) and at high latitudes (Franz Joseph Land, USSR), (Juramy et al., 1981). Because the daytime sky produces very high background photocount rates in most sodium lidar receivers, the majority of the lidar observations of the layer have been restricted to nighttime.
KeywordsLidar System Lidar Measurement Lidar Observation Altitude Profile Sodium Layer
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