Title: Dependence of street canyon concentrations on above-roof wind speed - implications for numerical modelling

Authors: M. Ketzel, R. Berkowicz, W.J. Muller, A. Lohmeyer

Addresses: National Environmental Research Institute, Frederiksborgvej 399, DK-4000 Roskilde, Denmark. National Environmental Research Institute, Frederiksborgvej 399, DK-4000 Roskilde, Denmark. Niedersachsisches Landesamt fur Okologie, Gottinger Strase 14, D-30449 Hannover, Germany. Lohmeyer Consulting Engineers, Mohrenstrase 14, D-01445 Radebeul, Germany

Abstract: For microscale numerical modelling of street canyon air pollution, the traffic-related component of the total ambient pollutant concentration is often assumed to be inversely dependent on the wind-speed at rooftops for idealised conditions of neutral stratification, no solar radiation, and no traffic-induced turbulence. Detailed data analyses of two comprehensive datasets from Gottinger Strase (Hannover) and Jagtvej (Copenhagen), including concentration and wind-field measurements in the street and above the rooftops, are presented to test these idealised assumptions, and to improve numerical modelling for a wider range of conditions. The experimental results show systematic deviation from the idealised inverse wind-speed law, when rooftop wind-speeds were less than 10 m/s. It was found that turbulence associated with traffic is a parameter, which is increasingly important for lower wind-speeds.

Keywords: air pollution modelling; field measurements; street pollution models; traffic-induced turbulence; traffic pollution.

DOI: 10.1504/IJEP.2002.000678

International Journal of Environment and Pollution, 2002 Vol.17 No.4, pp.356-366

Published online: 14 Jul 2003 *

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