A Better Way to Illustrate Atmospheric Dispersion in the Classroom

Students enrolled in introductory air pollution courses typically have difficulty fully understanding the impacts of changing variables in the Gaussian plume equation.It is challenging for students to visualize how the entire plume changes as the result of modifications in atmospheric stability, for example, since they typically calculate only one or two values in x, y, and z.Spreadsheets can help with completing these calculations quickly, but unfortunately can only plot in one dimension, and the results are still difficult to visualize.To address these limitations a Geographic Information System (GIS) based custom application was developed that coupled ESRI's ArcMap 9.1 with Matlab.Using inputs of stack height, wind speed, atmospheric stability, and source emission rate, the application creates an array of downwind ground level plume concentrations that are plotted onto a city map.The sum of these concentrations on the city's features such as schools are calculated.Though this application creates only a simplified model of the atmospheric dispersion process, it proves valuable in instruction since it is simple enough for students to understand, while at the same time demonstrating the dispersion process' "big picture."Students in an introductory air pollution course not only effectively employed the application to visualize the impact of changing plume variables, but also applied it to an optimization scenario that required repeated calculations of the downwind effects of various plumes to meet given concentration guidelines.After using this plume modeling application in the course, students had a better understanding of plume behavior, a better understanding of the value of information technology in solving engineering problems, and a greater interest in applications of atmospheric dispersion modeling.