Determination of Vertical Distributions of Aerosol Optical Parameters by Use of Multi-Wavelength Lidar Data

概要

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A lookup table (LUT) method is proposed to derive vertical distributions of aerosol optical parameters in the troposphere from multi-wavelength observations using a Mie-scattering lidar. A LUT is constructed by means of Mie-scattering calculations. For aerosol size distributions, we assume eleven models including the urban and maritime models as two extreme cases. For the aerosol refractive index, the imaginary part is changed between 0.0 and 0.03 in steps of $1.0\times 10^{-4}$, and the real part between 1.40 and 1.60 in steps of 0.01. The observed wavelength dependence of the lidar signal is compared with that of the LUT to determine the aerosol extinction coefficient, size distribution, refractive index, and the extinction-to-backscattering ratio ($S_{1}$ parameter) for each altitude. We apply the method to analyze data obtained with a four-wavelength lidar (355, 532, 756, and 1064 nm) operated at Chiba University. Compared with the conventional analysis with the Fernald method, the LUT approach has the advantage that it is capable of giving detailed optical parameters simultaneously with the extinction coefficient. Besides, since the analysis starts at the near-end boundary, the effect of detection noise becomes less influential.
INSTITUTE OF PURE AND APPLIED PHYSICSの論文
2003-02-15