Research On Key Technologies Of New Rayleigh Doppler Lidar System Based On Iodine Molecule Absorption Cel

The continuous observation of the temperature and wind in the middle and upper atmosphere with high spatial and temporal resolution can promote the research on the dynamical processes in the middle and upper atmosphere and improve the accuracy of the numerical atmospheric model results.In order to observe the atmospheric density,temperature and wind field at 30 km-70 km with high spatial and temporal resolution,a Rayleigh Doppler Lidar system was developed by Nanjing University of Information Science & Technology.This paper focuses on several key technical issues related to the above-mentioned LIDAR system:(1)Simulation is an important tool to evaluate the detection performance of Rayleigh Doppler LIDAR systems.In this paper,from the system detection principle,the minimum average emitted laser power to meet the design detection error index and the maximum emitted laser single pulse energy under the linear output limitation of the photomultiplier tube are analyzed using simulation and quantitative analysis,respectively.The background atmospheric model of the area where the lidar system will be installed was reconstructed by using atmospheric models and satellite observations.The expected detection performance of the Rayleigh Doppler LIDAR in the region was simulated.(2)This paper provides the first attempt to use a seeder multi-stage series direct amplification multiplier laser and multi-channel time-division multiplexing signal transceiver technology in the Rayleigh Doppler lidar for mid-atmosphere sounding.The total signal integration time is reduced by increasing the number of integration pulses per unit time and improving the efficiency of multi-channel signal transceiving and transmitting to achieve the purpose of improving the time resolution.In the process of sending and receiving the atmospheric echo signal,the multiplier 532 nm laser from the seed laser unit is introduced into the discriminating receiver for frequency measurement in a time-division multiplexed manner.Simultaneous measurement of the laser atmospheric echo signal and the emitted laser frequency is realized to provide an accurate zero Doppler frequency shift reference for wind speed measurement.(3)In this paper,The sensitivity of the transmittance response function of iodine molecular absorption cell to atmospheric temperature changes was studied,and a measured temperature-corrected transmittance response function calculation method for iodine molecular absorption spectroscopy single-edge Doppler discriminant technique was proposed according to the actual operating conditions of the system.The results of the inversion of the field observation show that the measured error of temperature is 2.4 K@60km and the measured error of horizontal wind speed is 8.7m/s and 8.5 m/s@60km in the meridional and zonal direction under the conditions of30 minutes time resolution and 1 km vertical height resolution,respectively.Comparison with the ECMWF atmospheric model and TIMED\SABER satellite soundings shows a good agreement.The reliability of the system for atmospheric temperature and wind field detection results is validated effectively.