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NIRE Annual Report
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 1999

Measurement of Size Distribution of Aearosol by Bistatic System

Air Quality Measurement Division
Atmospheric Environmental Protection Department
Objectives
We have used a multiwavelength laser to evaluate the size distribution of aerosol. The scattered light was measured with a bistatic lidar system using an 8-wavelength laser beam as the light source at a 179 degree scattering angle. This report presents a result of measurement of size distribution of fog and ambient aerosol of suspended particulate matter in the atmosphere.
Results
Two types of aerosols were observed for 2 successive days and were measured with the optical particle counter (OPC) at the same time at National Institute for Resources and Environment in Tsukuba (Fig. 1). The fog which was 26 m in front of the apparatus and 1.2 m high was measured with the bistatic lidar system.
The fog was essentially equivalent to a monodisperse system with a particle mode radius of 0.5~0.6mm. It is noticed that the number concentration of the inverted solution using an imaginary part of 0.001 is in good agreement with the OPC data.
Ambient aerosol was examined when the resuspension of fine particles from the ground was low and relative humidity was 67%. Fine particles from automobile exhaust seemed to be the main aerosol constituent. The inverted solution using the refractive index (1.5, 0.0) generally showed the Junge distribution.
Fig.1. Estimated size Distribution of ambient aerosol particles and fog
Fig. 1 Estimated size Distribution of ambient aerosol particles and fog
Selected Publications
1) Derivation of the Aerosol Size Distribution from a Bistatic System of a Multiwavelength Laser with the Singular Value Decomposition Method, Appl. Opt. 35, 2642-2648(1996).
2) Measurement of Particle Size Distribution of Ambient Aerosol by Bistatic Lidar System, J Aerosol Res., Jpn., 14(2), (1999)

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