Author(s)

U. Koren & W. Eichinger

Abstract

Road transport is recognized as the major anthropogenic pollution source in urban areas worldwide. To predict the impact of emissions from automobiles on ambient air quality, different mathematical models have been developed, primarily based on the Gaussian plume equation. However there are few field data sets that could be used to evaluate these models. The lidar (Light Detection and Ranging) technique has been used to determine relative particle concentration over the streets of Iowa City, Iowa in December 2001. An important input to diffusion models is the emission rate of pollutants to the atmosphere, the so called emission inventory. Due to insufficient direct emission measurements, emission rates are usually estimated from mass balance calculations. A method has been developed for indirect determination of emission rates, mean wind speed and vertical diffusivity by inversion of the Gaussian model for diffusion from a line-source. To solve the inversion problem, a Newton-Raphson method has been used. 1 Introduction Road transport is the major anthropogenic pollution source in urban areas (Montser- rat [l]). It is caused with the widespread use of gasoline as a motor fuel. Auto- mobile exhaust was recognized as a potential air pollutant around 1915, however it was not until about 1945 that the first urban air pollution problem definitely attributable to automobile emissions appeared in Los Angeles (Degobert [2]). This type of air pollution now occurs worldwide in any urban area in which there is a heavy use of automobiles. To predict the impact of emissions from automobiles on ambient air quality, different mathematical models have been developed. Most of them are based on the Gaussian plume equation (CALINE (Benson [3]), CAR-

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