Research On Near Infrared Raman Lidar For Detecting Atmospheric Aerosol

In this study,a new method is proposed that using the Raman lidar to detect aerosol optical parameters to solve the difficulty of independent detection at near-infrared wavelength.The character of Raman spectrum at near-infrared wavelength(1064nm)is researched and choose two scatter spectrum scales(1051nm-1061nm,068nm-1079nm),they are not influenced by temperature.According to Mie and Raman scatter spectrum,a near-infrared Raman detect spectroscope system is designed based on grating-differential.The system consists of raster,long lens,speculum with small aperture and lens with large relative aperture,the signal of Mie and Raman can be separated by them.The Raman channel hold 10-4 suppression ratio to signal of Mie.This spatroscope system get great SNR and collect the stokes and anti-stokes of Raman scatter signal at the same time.By using the atmosphere model of haze day and cloudy,the detect ability of this system can be analiysed and simulating calculated.With the calculation outcome,this system can carry out the high precision detection of aerosol within boundary layer(4.5km)under the haze day(visibility 1km),meanwhile,the high precision detection of cloud layer optical parameters can be conducted under any weather condition.In this study,a Raman lidar at 1064nm experiment system was built,by using a series of aerial survey data and an algorithm of adaptive reference height,the system constants can be calibrated.The system constants of any weather condition and any experimental condition can be inferred,and the constants can inverse the ratio of backscattering coefficient.We use this system to study the aerosol in Xi'an,according to the inversion of Raman and got the backscattering coefficient profile,extinction coefficient profile at 1064nm.The capability of this system can be proved by comparing the data of this system and the Raman lidar system at 355nm.Using the system detects optical parameters of aerosol under different weater condition and analyses the changing process of aerosol in any condition.