Lidar observations of the nighttime sodium layer at 33 deg N

Measurements of the nighttime atmospheric sodium layer have been performed since 1977, using a dye lidar at Fukuoka (33.4 deg N, 130.2 deg E.). The Kyushu lidar uses a flashlamp pumped dye laser tuned to the sodium D sub 2 line (589.0 nm) as a transmitter. The dye laser used in the Kyushu lidar system has been described elsewhere. Sporadic enhancements of the total column abundance of the layer during the Perseids meteor shower were observed on the nights of August 12 and 13, 1978, 1979, 1981, and 1983. Degrading weather conditions prevented observation on the nights during 1980 and 1983. A contour plot of the sodium layer for the period of 8 hours from 21:00 to 5:00 JST on the night of August 12 to 13 1983, is shown. The predominant feature visible is the increase in the height of peak density from 21:00 to 2:00 JST, and the slight decrease in the height of peak density from 2:00 to 5:00 JST. The average abundance had a maximum of about 7 x 10 to the 13th power/sq m on August 13. A plot is presented of the nightly average abundance for available data. The sodium layer abundance increased on the night of August 12 to 13, 1983, during the peak of the Perseids meteor shower, and the following night, August 13 to 14, almost went back to the monthly mean.