A. Micallef et Jj. Colls, Measuring and modelling the airborne particulate matter mass concentrationfield in the street environment: model overview and evaluation, SCI TOTAL E, 235(1-3), 1999, pp. 199-210
This paper discusses the outline structure and preliminary evaluation of an
emission-dispersion model for predicting the temporal and spatial distribu
tion of vehicle-derived airborne particulate matter mass concentration in s
treet canyons. The model is called Street Level Air Quality (SLAQ). SLAQ is
semi-empirical, in that it uses not only results from field and wind tunne
l experiments but also theory and models derived from multiple runs of nume
rical routines in order to simulate the basic physical processes within the
street canyon. A combination of a plume model, for the direct contribution
of vehicle exhaust, and a box model for the recirculating part of the poll
utants in the street, is used to predict concentration for receptors within
the canyon. Emission rates of vehicle-derived particulate. matter are calc
ulated within SLAQ, which serve as input to the dispersion module. Exhaust
emission rates are scaled element by element along the street for each of t
he lanes according to the direction of traffic flow to account for modal op
eration of vehicles near signalised intersections. This refinement allows S
LAQ to account for non-uniformity in along-canyon emission rates and to mod
el a street that has several intersections along its length. Thermal turbul
ence due to environmental surface sensible heat and vehicle-generated heat
is accounted for in the model. Other features of SLAQ include correction fo
r the urban heat island effect, dry deposition, wet deposition, particle se
ttling and estimation of wind direction standard deviation, when this latte
r data is not available. SLAQ has been evaluated in a street in Loughboroug
h, Leicestershire, United Kingdom and a correlation coefficient of 0.8 betw
een the modelled and measured concentrations has been obtained. (C) 1999 El
sevier Science B.V. All rights reserved.