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EVALUATION AND SENSITIVITY ANALYSES RESULTS OF THE MESOPUFF II MODEL WITH CAPTEX MEASUREMENTS
Citation:
Godowitch, J. EVALUATION AND SENSITIVITY ANALYSES RESULTS OF THE MESOPUFF II MODEL WITH CAPTEX MEASUREMENTS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/3-89/056 (NTIS PB89198253), 1989.
Description:
The MESOPUFF II regional Lagrangian puff model has been evaluated and tested against measurements from the Cross-Appalachian Tracer Experiment (CAPTEX) data base in an effort to assess its abilIty to simulate the transport and dispersion of a nonreactive, nondepositing tracer plume out to distances of over 1000 km. The model applied a mixed-layer averaged wind field to simulate boundary layer transport and Gaussian dispersion parameters to govern puff growth. The model was executed to simulate the plume formed by the 3-hour ground-level release of a perfluorocarbon tracer gas from either Dayton, Ohio or Sudbury, Ontario for six cases. Model performance was quantitatively determined from traditional statistical measures of difference and correlation between modeled and observed concentration pairs measured at 3-h or 6-h intervals. The model overpredicted peak and mean concentrations; modeled mean values were within a factor of two of observed values in four experiments. Graphical maps confirmed that the scatter among concentration pairs was primarily due to notable spatial displacements between observed and modeled tracer plumes. Analysis of plume centroid positions was employed to give quantitative information about the difference in downwind distances and separation between the observed and modeled plume patterns versus time. Diagnostic test run results, where optional single level wind fields and optional dispersion methods were exercised, are also compared to default model run results and to observed values. Sensitivity test runs focused on variations in the dry deposition and chemical transformation parameters for SOx.