Evaluation of a modelling system for predicting the concentrations of PM_2.5 in an urban area

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• 作者：M. Kauhaniemi ; A. Karppinen ; J. H&#xe4 ; rkö ; nen ; A. Kousa ; B. Alaviippola ; T. Koskentalo ; P. Aarnio ; T. Elol&#xe4 ; hde ; J. Kukkonen
• 关键词：Urban pollution ; Model ; Evaluation ; PM_2.5 ; CAR-FMI
• 刊名：Atmospheric Environment
• 出版年：2008
• 期刊代码：11_13522310
• 类别：env
• 出版时间：June 2008
• 卷：42
• 期：19
• 页码：4517-4529
• 文件大小：3364 K

摘要

We present a modelling system that contains a treatment of the emissions and atmospheric dispersion of fine particulate matter (PM_2.5) on an urban scale, combined with a statistical model for estimating the contribution of long-range transported aerosols. The model of PM_2.5 emissions includes exhaust emissions, cold starts and driving, as well as, non-exhaust emissions originated from urban vehicular traffic. The influence of primary vehicular emissions from the road and street network was evaluated using a roadside emission and dispersion model, CAR-FMI, in combination with a meteorological pre-processing model, MPP-FMI. We have computed hourly sequential time series of the PM_2.5 concentrations in 2002 in a numerical grid in the Helsinki Metropolitan Area. The predicted results were compared against measured data at two locations in central Helsinki: urban roadside station of Vallila and urban background station of Kallio. The predicted daily average PM_2.5 concentrations agreed well with the measured values; e.g., the index of agreement values were 0.83 and 0.86 at Vallila and Kallio, respectively, and the absolute values of fractional bias mg src="http://www.sciencedirect.com/scidirimg/entities/2a7d.gif" alt="less-than-or-equals, slant" title="less-than-or-equals, slant" border="0">0.13. As expected, the scatter of data points is substantially wider for the hourly concentration values; e.g., the index of agreement values were 0.69 and 0.74. We also computed the spatial concentration distributions of PM_2.5. The predicted contribution from long-range transport to the street level PM_2.5 varied spatially from 40%in the most trafficked areas to nearly 100%in the outskirts of the area. The emissions originated from cold starts and driving were responsible for <4%of the annual average concentrations at the roadside and urban stations. The model can potentially be used as a practical tool of assessment of urban PM_2.5 contributions in various European regions.