Abstract

A multiple wavelength, pulsed CO₂ lidar system is used to measure spectral backscattering and extinction of kaolin dust of different optical thicknesses. The measurements show that the wavelength dependence of spectral backscattering changes with increased multiple scattering, whereas the spectral extinction remains relatively unchanged. A simple analytical two-stream radiative transfer model is used to confirm the measurements qualitatively. Several equations were derived from the model to show that in general the wavelength dependence of backscatter is less dependent on wavelength for a multiple-scattering case. Therefore, the aerosol cloud becomes a diffuse target that is more flat in its spectral reflectance as multiple scattering increases. An application to differential absorption detection is discussed and shows that, in general, the effect of multiple scattering on the backscattered signal from aerosols will tend to reduce the error in deducing the average path-length concentration of the absorbing trace gas.

© 1993 Optical Society of America

Multiple-scattering effects on differential absorption for the transmission of a plane-parallel beam in a homogeneous medium

Avishai Ben-David
Appl. Opt. 36(6) 1386-1398 (1997)

Multiple-scattering influence on extinction- and backscatter-coefficient measurements with Raman and high-spectral-resolution lidars

Ulla Wandinger
Appl. Opt. 37(3) 417-427 (1998)

Lidar multiple scattering: improvement of Bissonnette's paraxial approximation

Matthias Wiegner and Georg Echle
Appl. Opt. 32(33) 6789-6803 (1993)

Carbon dioxide laser backscatter signatures from laboratory-generated dust

Diane Powell Walter, David E. Cooper, Jan E. van der Laan, and Edward R. Murray
Appl. Opt. 25(15) 2506-2513 (1986)

Backscatter and extinction measurements in cloud and drizzle at CO₂ laser wavelengths

S. G. Jennings
Appl. Opt. 25(15) 2499-2505 (1986)