Study On Calibration Technology Of Raman-Mie Aerosol Lidar

Aerosol lidar has the advantages of high space-time resolution and high accuracy.In recent years,it has been widely used as a means of observing haze and measuring aerosol extinction coefficient and backscatter coefficient.However,due to the hardware problems and inversion algorithms of aerosol lidar,the extinction coefficients and backscatter coefficients of aerosols cannot be obtained accurately and quantitatively.In this paper,first the hardware and the inversion algorithm are calibrated separately for different types of aerosol lidar placed in the same location.Then the comparison between the measured echo signals and the actual measured backscatter coefficients of the multiple aerosol lidar is carried out.The accuracy of the aerosol backscatter coefficient measurement has been initially achieved and quantified.The main contents and conclusions of this paper are as follows:1)This article will propose a series of hardware calibration methods to solve the problem of signal distortion caused by the internal parts of the lidar hardware has been assembled radar.Improve the coaxiality of the emission optical axis and the receiving optical axis of the lidar.Increase the rationality of echo signals when there are only atmospheric molecules in high altitude.2)This paper compares the aerosol extinction coefficient and backscatter coefficient of different models of lidar using simulated Mie scattering and Raman scattering echo signals,and verifies the accuracy of the inversion algorithm.The average absolute deviation of the backscattering coefficients of all lidar systems using m-scattered echo signals is less than 9.5*10-8m-1sr-1,and the average relative deviation is less than 17.5%.The average absolute deviation of the lidar system using the extinction coefficient of the Raman scattering echo signal is less than 9*10-6m-1,and the average relative deviation is less than 30%.The average absolute deviation of the backscatter coefficients of the lidar system combined with the Mie scattering and Raman scattering echo signals is less than or equal to 9*10-8m-1sr-1,and the relative deviation of the average percentage is less than 20%.3)This paper compares the radar echoes measured by all radar systems to determine whether the echo signal in the low air is reasonable.If it is not reasonable,make adjustments to improve the accuracy of low-air echo signals.Afterwards,the backscatter coefficients of actual aerosol inversion are compared.In addition to being affected by the geometrical overlap factor,their average absolute system deviation is between ±2.3*10-7m-1sr-1.It shows that the backscatter coefficient has certain accuracy.4)These calibrated aerosol lidars was distributed to different areas of Beijing,and a haze process was monitored.The results show that several aerosol lidars can perform a joint observation of the pollution process and can provide the difference in the spatio-temporal distribution of pollutants monitored by the same pollution process in the vertical direction at different locations at the same time.