Retrieval of complex refractive index from lidar measurements: possibilities and limitations
S.V. Samoilova
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
Keywords: aerosol, lidar, particle size distribution, complex refractive index
Abstract
Studies of indeterminacy of the complex refractive index m = mR + imI estimation and simulation results with respect to the analysis of the retrieval error of aerosol microphysical properties from multiwavelength lidar data (355 and 532 nm for extinction and 355, 532, and 1064 nm for backscatter) are presented. It is shown that m is not found unambiguously in the error-presence conditions, because a flat valley on (mR, mI ) plane corresponds to a set of optical coefficients values. Accuracy of estimation of aerosol microphysical properties for bimodal size distribution function U(r) depends on the value of the contribution of small particles into the volume concentration. Mean errors are ΔmR ~ 3.5%, ΔmI ~ 80% for joint reconstruction of m and U(r) and 10% input noise. Lidar ratio information allows the error of reconstructing the single-scattering albedo to be at least halved.
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