Dispersion modeling in support of regulatory programs for federal, regional, state and localpermitting relies on the U.S. Environmental Protection Agency’s AERMOD Model as specifiedin the Guideline on Air Quality Models (40 CFR 51, Appendix W).1 Internal calculations inAERMOD for daytime mixing in the convective boundary layer and night time mixing in thestable boundary layer rely on surface land use. Three variables are derived from land use datausing EPA’s AERSURFACE2 Program, namely, albedo, Bowen ratio, and the surface roughnessparameter. The purpose of this study was to demonstrate the sensitivity of the AERMOD3Model in modeling identical sources with meteorological data sets derived using both airport andindustrial site land use characteristics. This paper (using the results of a companion study ofland use and the derivation of these three variables with variable surface roughness) presentscombinations of meteorological data sets with representative industrial facility point and volumesources representing stacks, transfer points, storage piles and roads. Meteorology from variousU.S. regions is used along with the land use characteristics for each airport and an urbancomplex where industrial activities are likely. Flat terrain is assumed in all cases. Comparisonsbetween estimated concentrations for the various source types and meteorological data sets onboth an annual basis and on a short-term averaging time basis show the importance of selectingspecific land use and the possible variability that will result when following modeling guidancefrom states and regions on the selection of the appropriate location to use to determine therepresentative land use.
`Sensitivity of Aermod to meteorological data sets based on varying surface roughness,` presented at the 2009 air & waste management association`s annual conference