Doppler Frequency Correction Of Rayleigh Wind Lidar And Gravity Waves Observation

High-precision wind and temperature observation data of the middle and upper atmosphere(20?120km)is one of the important foundations for the study of atmospheric dynamics,atmospheric models and space weather.Lidar(Light Detection and Ranging)which can continuously observe atmospheric temperature,density and wind speed,was offen used in the middle and upper atmosphere detection and gravity waves observation research.Due to the lack of tracers in the stratosphere to middle layer atmosphere and balloons and other observation equipment are also difficult to reach,it has always been a difficult part in atmospheric observation.So far,only a few lidar systems such as the vehicle-mounted Doppler lidar of the University of Science and Technology of China and the RMR of the ALAMOR observatory can achieve continuous observation of wind speed and temperature in this area.According to the simulation results of the lidar system,the paremeters of each component are determined and tested after constructed.We studied on the key technology of Doppler frequency calibration,to solve the Doppler frequency drifting problem which has always been a difficulty for wind lidar system.Based on the long-term measurement wind and temperature data of this Rayleigh lidar,the inertial gravity waves of the stratosphere and the middle layer are carried out.The extraction method and the statistical analysis of long-term observations of gravity waves were demontrasted.We analyzed the distribution characteristics of gravity waves from the stratosphere to the middle atmosphere,and explained in combination with local climate and geographical conditions.The main work of this dissertation can be summarized as three parts:Firstly,we studied the measurement principle and wind speed inversion method of the Rayleigh wind measurement lidar system.According to the project requirements,the system performance simulation was demontrasted to determine the performance indicators of the main components of the lidar system,and completed the system hardware performance testing.Secondly,with continuously monitoring of the laser frequency and optical receiver transmittance,it was found that the problem of Doppler frequency drift were mainly caused by the laser frequency jitter and the optical instability.Through the development of three key technologies of laser frequency locking,response function calibration and Doppler frequency calibration,the Doppler frequency drift was eliminated.Observation experiments show that in a typical continuous observation time(8 hours),the standard deviation of the atmospheric horizontal wind speed at a height of 20km is less than 5m/s,and the wind speed is consistent with the observation results ballon-sonde.Finally,the wind and temperature perturbation analysis was performed based on the wind and temperature observation data of this Rayleigh wind in Xinjiang,China.Filtering,gravity wave model parameter fitting,Hodograph and other methods were used to calculate the amplitude,vertical and horizontal propagation characteristics,period and other parameters of the quasi-monochromatic inertial gravity waves.From the 224 hours data accumulated by Rayleigh lidar,a gravity wave event of 384/waves/time was extracted.Statistical analysis of all these gravity wave events was performed and the dominant propagation and period distribution were explained in combination with the geographical and climatic conditions of the observation site.