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USER'S GUIDE FOR THE PHOTOCHEMICAL BOX MODEL (PBM)
Citation:
Schere, K. AND K. Demerjian. USER'S GUIDE FOR THE PHOTOCHEMICAL BOX MODEL (PBM). U.S. Environmental Protection Agency, Washington, D.C., EPA/600/8-84/022B.
Description:
The User's Guide for the Photochemical Box Model (PBM) attempts to describe the structure and operation of the model and its preprocessors as well as provide the potential user with guidance in setting up input data. The PBM is a simple stationary single-cell model with a variable height lid designed to provide volume-integrated hour averages of O3 and other photochemical smog pollutants of interest for an urban area for a single day of simulation. The PBM is most appropriate for application in air stagnation conditions with light and variable winds. Horizontal dimensions of the box are typically on the order of 10-50 km; the vertical dimension may vary between 0.1 and 2 km. Chemical reactions are simulated using a 63-step kinetic mechanism that includes diurnal variation of photolytic rate constants. The depth of the mixed layer also follows a diurnal pattern. The PBM assumes that emission sources are homogeneously distributed across the surface face of the box volume and that the volume is well mixed at all times. Atmospheric diffusion and wind shear are neglected. The user must provide the PBM with initial species concentrations, hourly inputs of wind speed, source emission fluxes of CO, NOx, THC, and hydrocarbon reactivity classes, and boundary species concentrations. Values of measured solar radiation and mixed layer depth may be specified at sub-hourly intervals throughout a simulation. The services of a qualified dispersion meteorologist, a chemist, and a computer programmer may be necessary to implement and apply the PBM and to interpret the results.