Optical EngineeringNarrowband lidar technique for sodium temperature and Doppler wind observations of the upper atmosphere
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We describe a new two-frequency lidar for measuring mesospheric Na temperature profiles that uses a stabilized cw single-mode dye laser oscillator (rms frequency jitter < 1 MHz) followed by a pulsed dye power amplifier (140 MHz FWHM linewidth) that is pumped by an injection- locked Nd:YAG laser. 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 our initial observations of the temperature profile between 82 and 102 km at Ft. Collins, CO (40.6°N, 105°W) are described. Absolute temperature accuracies at the Na layer peak of better than ±3K with a vertical resolution of 1 km and an integration period of approximately 5 mm were achieved in this initial experiment. Finally, we discuss a multiple frequency technique for the simultaneous measurement of both temperature and Doppler wind profiles.