Implementing and Evaluating an Igor-Compatible Reactive Gaussian Plume Model

High concentrations of tropospheric ozone are harmful to human respiratory health and damaging to vegetation. Despite regulations on ozone precursors, power plant emissions of nitrogen oxides (NOx) continue to generate unhealthy levels of near-surface ozone in regions where biogenic sources of Volatile Organic Compounds (VOCs) are high. To understand where levels of ozone and other harmful chemicals are most concentrated, a computer model was developed to simulate the dispersion of point source emissions and the continuous atmospheric chemistry they undergo. This model was developed in the programming language Igor Pro, to be compatible with existing research tools, and models plume dispersion in both the crosswind and vertical directions. The model assumes such dispersion follows Gaussian distributions, the standard deviations of which are a function of both atmospheric conditions and downwind distance. To enable researchers to fit the model to in situ airborne data, the model allows users to modify the dispersion rates, atmospheric conditions, chemical species of interest, their background concentrations, their chemical reactions, emission rates, and the model resolution. To test the model, the output was compared to data from NOAA’s 1999 Southern Oxidant Study and found to match with a 1.63% average error in reactive nitrogen (NOy) crosswind concentrations. Such accurate initial results indicate this model may be useful for researchers interested in developing a more complex picture of how power plant and other point source emissions, particularly ozone precursors, disperse and react chemically in the atmosphere.