Optical extinction dependence on wavelength and size distribution of airborne dust
Document ID: 211
Pangle, Garrett E.
Hook, D. Adam
Long, Brandon J. N.
Philbrick, C. Russell
Hallen, Hans D.
North Carolina State University, Department of Physics, Raleigh, NC, U.S.A.
Abstract
The optical scattering from laser beams propagating through atmospheric aerosols has been shown to be very useful in describing air pollution aerosol properties. This research explores and extends that capability to particulate matter. The optical properties of Arizona Road Dust (ARD) samples are measured in a chamber that simulates the particle dispersal of dust aerosols in the atmospheric environment. Visible, near infrared, and long wave infrared lasers are used. Optical scattering measurements show the expected dependence of laser wavelength and particle size on the extinction of laser beams. The extinction at long wavelengths demonstrates reduced scattering, but chemical absorption of dust species must be considered. The extinction and depolarization of laser wavelengths interacting with several size cuts of ARD are examined. The measurements include studies of different size distributions, and their evolution over time is recorded by an Aerodynamic Particle Sizer. We analyze the size-dependent extinction and depolarization of ARD. We present a method of predicting extinction for an arbitrary ARD size distribution. These studies provide new insights for understanding the optical propagation of laser beams through airborne particulate matter.
Keywords: aerosol scattering, optical extinction, non-spherical particles, Arizona Road Dust (ARD)
| Citation: | "Optical extinction dependence on wavelength and size distribution of airborne dust", Pangle, G. E., D. A. Hook, B. J. N. Long, C. R. Philbrick, H. D. Hallen, Laser Radar Technology and Applications XVIII, Vol. 8731, SPIE, 2013, pp. 87310N-1 - 87310N-14, DOI: 10.1117/12.2017850, CCC: 0277-786X/13 |