Applied urban dispersion modeling with OML-Urban

What's it all about?

For single, high stack source configurations, Gaussian plume models give acceptable results. This is due to the fact that the condition of surface homogeneity is (more or less) fulfilled. Nowadays severe air pollution problems arise in the ever-growing cities. Built-up areas feature a different turbulence structure. It is shown for a specific example which adaptations in the use and computing code of an applied Gaussian plume model have to be undertaken in order to apply it to urban environments.

Modification of the OML

An operational multi-source, multi-receptor Gaussian dispersion model, the Danish regulatory model OML, has been modified for applications in urban environments. A so-called roughness sublayer has been introduced into the model to represent the turbulence characteristics of the lowest part of the surface layer over rough surfaces like cities. The meteorological preprocessor was enhanced to take into account an urban energy budget. The performance of the resulting OML-Urban has been validated for NOx and SO2 for the city of Zurich for the year 1990. For this year, a detailed emission inventory as well as continuous hourly measurements at four stations are available. The air pollution monitoring stations used for validation have been divided into different groups, depending on local influences from nearby roads. The urban modification (roughness sublayer and changes in the met. preprocessor) results in a 25-35% increase of the annual mean surface concentration. OML-Urban shows a good reproduction of the probability density function of predicted concentrations, and the simulated yearly averaged concentrations show a good correspondence to observations.

Further information...

...can be found in Chapters 6 and 7 of my PhD.
... or in the paper Modification of an Operational Dispersion Model for Urban Applications.
Or send me an e-mail:

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