Technique for determining mass concentrations of aerosol fractions in the surface air from multifrequency lidar sounding data

摘要

A technique for determining mass concentrations of aerosol particles smaller than 1.0, 2.5, 10, and 30 μm in the surface air is suggested. The technique involves remote lidar sounding of the atmosphere at the wavelengths λ = 0.355, 0.532, 1.064, 2.13 μm, retrieval of the spectral and spatial distributions of the aerosol extinction coefficient from the lidar signals, and their conversion to the spatial distributions of the concentrations of aerosol fractions on the basis of regression relations between optical and microphysical aerosol parameters. To improve the accuracy and stability of the solution of a system of lidar equations, the calibration constants and lidar ratios at the wavelengths of the sounding radiation are chosen taking into account the multicollinearity of the spectral aerosol extinction coefficients, which is expressed in the form of a multiple regression equation. The regressions were derived within the World Meteorological Organization’s optical model of urban aerosol under wide variations in model parameters which characterize the particle size distribution and the complex refractive index of the aerosol matter. Numerical experiments on remote laser sounding of the mass concentration of aerosol fractions in the atmosphere have shown the robustness of the technique proposed.