Light scattering characteristics of various aerosol types derived from multiple wavelength lidar observations

Abstract

The present study demonstrates the potential of a multiple wavelength lidar for discriminating between several aerosol types such as maritime, continental, stratospheric, and desert aerosols on the basis of wavelength dependence of the aerosol backscatter coefficient. In the analysis of lidar signals, the two-component lidar equation was solved under the assumption of similarity in the derived profiles of backscatter coefficients for each wavelength, and this made it possible to reduce the uncertainty in the extinction/backscatter ratio, which is a key parameter in the lidar solution. It is shown that a three-wavelength lidar system operating at 300, 600, and 1064 nm can provide unique information for discriminating between various aerosol types such as continental, maritime, Saharan dust, stratospheric aerosols in a tropopause fold event, and tropical forest aerosols. Measurement error estimation was also made through numerical simulations. Mie calculations were made using in situ aerosol data and aerosol models to compare with the lidar results. There was disagreement between the theoretical and empirical results, which in some cases was substantial. These differences may be partly due to uncertainties in the lidar data analysis and aerosol characteristics and also due to the conventional assumption of aerosol sphericity for the aerosol Mie calculations.