Two-frequency Lidar technique for mesospheric Na temperature measurements

This paper describes a new two-frequency lidar for measuring Na temperature profiles. The laser oscillator is tuned to the two operating frequencies by observing the Doppler-free structure of the Na D2 fluorescence spectrum in a vapor cell. The lidar technique and initial observations of the temperature profile between 82 and 102 km are described. Absolute temperature accuracies at the Na layer peak of better than + or - 3 K with a vertical resolution of 1 km and an integration period of approximately 5 min were achieved.