Urban pollution, simulation

The zero emission test is intended to quantify the sensitivity of the model to emissions. The model should produce concentrations close to background or at least representative of upwind concentrations. Insensitivity to emissions raises questions about the utility of the simulated scenario for design of control strategies. The zero (or as close to zero as possible) initial and boundary condition tests reveal the effect of these often uncertain conditions on predicted concentrations. This initial condition effect should be small for the second or third day of an urban-scale simulation. The expected results of the zero deposition tests are increases of the primary pollutant concentrations downwind of their sources. However, concentrations of secondary pollutants may increase or decrease during... 

Bornstein et al.. Simulation of Urban Earner Effects on Polluted Urban Boundary Layers Using the Three-Dimensional URBMET TVM Model with Urban Topography, Air Pollution Proceedings, 1993. 

Schere, K. L., and Demerjian, K. L., A photochemical box model for urban air quality simulation, in "Proceedings of the Fourth Joint Conference on Sensing of Environmental Pollutants." American Chemical Society, Washington, DC, 1978, pp. 427-433. 

PBM (Photochemical Box Model) is a simple stationary single-cell model with a variable height lid designed to provide volume-integrated hour averages of ozone and otlier photochemical smog pollutants for an urban area for a single day of simulation. 

Another classification of model is related to the time and space scales of interest. Ambient air quality standards are stated for measurement averaging periods varying from an hour to a year. However, for computational purposes, it is often necessary to use periods of less than an hour for a typical resolution-cell size in a model. Spatial scales of interest vary from a few tenths of a meter (e.g., for the area immediately adjacent to a roadway) up to hundreds of kilometers (e.g., in simulations that will elucidate urban-rural interactions). Large spatial scales are also warranted when multiday simulations are necessary for even a moderate-sized urban area. Under some climatologic conditions, recirculations can cause interaction of today s pollution with tomorrow s. Typical resolution specifications couple spatial scales with temporal sc es. Therefore, the full matrix of time scales and space scales is not needed, because of the dependence of time scales on space scales. Some typical categories by scale are as follows ... 

The model system is developed to simulate aerosols and gas-phase compounds from regional to urban scale of ground-level gas-phase air pollutants. It has been used for air quality forecasts of ground-level gas-phase air pollutants and modelling of historical data. 

Several types of models are commonly used to describe the dispersion of atmospheric contaminants. Among these are the box, plume, and puff models. None are suitable, however, for describing the coupled transport and reaction phenomena that characterize atmospheres in which chemical reaction processes are important. Simulation models that have been proposed for the prediction of concentrations of photochemically formed pollutants in an urban airshed are reviewed here. The development of a generalized kinetic mechanism for photochemical smog suitable for inclusion in an urban airshed model, the treatment of emissions from automobiles, aircraft, power plants, and distributed sources, and the treatment of temporal and spatial variations of primary meteorological parameters are also discussed. 

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