Abstract
A sodium fluorescence Doppler lidar system has been developed to measure environmental parameters of the middle and upper atmosphere. The lidar system mainly comprises a transmitter system, receiver system, data acquisition and control system and data analysis system. A narrowband 589 nm laser is used to excite sodium atoms in the mesopause region. Excitation of the sodium atoms results in resonance fluorescence, which is collected by the receiver. The temperatures in the mesopause region (about 75–105 km) can be derived by analyzing the Doppler-broadened width of the sodium fluorescence. Observations were made with the lidar system, and the number density of sodium atoms and atmospheric temperature profiles were extracted from the observation data. Comparisons of the lidar temperatures and TIMED/SABER temperatures show good agreement, illustrating the reliability of the sodium fluorescence Doppler lidar measurements.
Highlights
A sodium fluorescence Doppler lidar system has been developed to measure environmental parameters of the middle and upper atmosphere
The mesopause region is an area of strong coupling between the lower and upper atmosphere
The first observation of the sodium hyperfine structure in the middle and upper atmosphere was reported by Gibson et al [13] in 1979, establishing the possibility of mesopause temperature measurements with narrowband resonance fluorescence lidar
Summary
Where σD is the root-mean-square width of the Dopplerbroadened line, vn and An are the central frequencies and the line strengths of six electric-dipole-allowed D2 transitions, v is frequency, vR is the radial velocity of the sodium atom moving away from the laser source and c is the speed of light. Sodium resonance fluorescence is induced by the laser. The lineshape of the resonance fluorescence spectrum is a convolution of the atom Doppler-broadened lineshape and laser lineshape gL(v), which can be expressed as.
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