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Proceedings Paper

Three-Wavelength Lidar Method To Measure Mass Concentration In An Unknown Pollutant Cloud
Author(s): S. Rafi Ahmad
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Paper Abstract

The mass concentration in a pollutant cloud can be estimated from the normalized range-corrected LIDAR signal S(R) if the clear-air mass concentration and the parameter Ω defined as the ratio of some weighted (by the product of the size distribution function and the square of the radius) average of the total scattering efficiency to the volume to surface average radius, are known. The ratio Ω can be calculated by numerically solving the LIDAR equation for three different wavelengths in terms of the observed quantities S(R,λ), the known values of the λ's and an assumed value of the refractive index m. In the present analyses, S-functions are simulated for log-normal size distributions with different values of the standard deviation. For simplicity spatially uniform number density is assumed so that only two-wavelength calculations are needed. Assumed mass concentrations (for different widths of the size distribution) are compared with those calculated using the modified LIDAR equation. The results show that the validity of the method is limited by the width of the size distribution and the product (R-Ro)N where (R-Ro) is the probed range inside the cloud and N is the number density.

Paper Details

Date Published: 15 May 1981
PDF: 8 pages
Proc. SPIE 0236, 1980 European Conf on Optical Systems and Applications, (15 May 1981); doi: 10.1117/12.959002
Show Author Affiliations
S. Rafi Ahmad, Royal Military College of Science (United Kingdom)

Published in SPIE Proceedings Vol. 0236:
1980 European Conf on Optical Systems and Applications
D. J. Kroon, Editor(s)

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