Retrieval of the aerosol extinction coefficient of 1064nm based on high-spectral-resolution lidar

Abstract

It is difficult to independently obtain aerosol optical parameters at the near-infrared wavelength using lidar. A new high-spectral-resolution technology is proposed to obtain the aerosol extinction coefficient profile at 1064 nm. The high-spectral-resolution detection method by extracting Mie scattering and suppressing Cabannes–Brillouin scattering is applied in the lidar at 1064 nm to improve the detection signal-to-noise ratio. The system parameters of near-infrared high-spectral-resolution LiDAR (NHSRL) must be calibrated in this method; then, the optical parameters are accurately deduced. The effect of the system parameters (transmittances of the spectral filter for molecule and aerosol) on the detection results in this method is discussed and analysed. The transmittance of the spectral filter for aerosol scattering is a key parameter in the retrieval of the extinction coefficient, and the sensitivity of the inversion results to the transmittance is analysed and discussed. The method to distinguish the large deviation data of the extinction coefficient is discussed and provided, and the third derivative of the optical thickness profile is adopted to determine the data. According to the characteristics of the inversion signal, the method to correct the extinction coefficient profile is also presented. The correction algorithm can obviously increase the inversion accuracy of the extinction coefficient. The 1064-nm NHSRL Lidar was developed at Xi'an University of Technology. A dual-channel Fabry-Perot Etalon was designed and used to extract the aerosol Mie scattering signal and suppress Cabannes–Brillouin scattering in this NHSRL. The NHSRL lidar observations were performed, and extinction coefficient profiles at 1064 nm were obtained. The results demonstrate that the method can obtain an accurate profile of the extinction coefficients.