Operational Evaluation of Volume Sources Using Duke forest Field Study

by Kuruvilla, Annie S

Abstract (Summary)
The performance of two volume source models, the US EPA’s AERMOD model and the Analytical Volume Source model (AVS) are evaluated by comparing it to a field study done in Duke Forest, North Carolina in the year 1995. The study was conducted from January 10th -26th 1995. For comparison purposes, the study has been categorized according to stability class, wind speed categories and down distance from the source. The downwind concentration prediction is compared for both the models, and the measures of correlation and scatter are determined. A case by case analysis has been done according to the stability conditions, wind speed and distance from the source. For stable cases, not enough data points are available from the study to make any recommendations. In the convective case, AVS model gives an overall better performance for normalized mean square error (NMSE) and fractional bias (FB). It was found out that the performance of the models vary with the wind speed categories. In the low, moderate and medium wind speed categories both the models are performing relatively well with a certain degree of over prediction in all three cases. For low wind speeds the overall prediction for the AVS model is good for NMSE and FB. For distances close to source the predictions of both AERMOD and the AVS model are good. Further downstream of the source, AVS model tends to over predict as compared to AERMOD. Further analysis done to predict the outliers of the observed and predicted concentrations indicated a significant variance in the values of the evaluated statistical parameters. But it meets the acceptable criteria for a good model reported in the literature. A study done to find out a balanced emphasis between observed and predicted concentrations indicated over predictions and under predictions for both the models. Confidence limit analyses on both the models verify the statistical parameters. NMSE and FB are significantly different in most of the convective cases.
Bibliographical Information:


School:University of Toledo

School Location:USA - Ohio

Source Type:Master's Thesis

Keywords:avs model aermod


Date of Publication:01/01/2005

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