||Computer Sciences Corp., Research Triangle Park, NC. ;National Oceanic and Atmospheric Administration, Research Triangle Park, NC. Atmospheric Sciences Modeling Div.;Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Research and Exposure Assessment Lab.
The Complex Terrain Dispersion Model (CTDMPLUS), described in Part I of the paper, was evaluated using the SO2 field study data from the Lovett Power plant in southeastern New York State. For additional perspective, CTDMPLUS estimates are also compared with those from the regulatory version of the Rough Terrain Dispersion Model. Comparing the highest 25 hourly observations with the highest 25 model predictions shows a tendency for CTDMPLUS to overpredict, on average, by about a factor of two. Similar results are found for 3-h and 24-h average predictions. Overpredictions occur mainly for stable atmospheric conditions. The meteorological conditions associated with the highest 25 observed concentrations are examined relative to the performance of CTDMPLUS. The analysis suggests that the most significant factors affecting CTDMPLUS predictions for stable conditions are the height of the plume and its relation to the dividing streamline, and in convective conditions the plume penetration, lateral plume spread, and wind direction.