When conducting an air dispersion modeling analysis with AERMOD, a common question arises as to what limits – if any – exist on where calculations can be performed by the model. Understanding the range of the model’s validity is important in interpreting results.
In the United States, the National Ambient Air Quality Standard (NAAQS) for Lead is 0.15 µ/m3 as a rolling three-month average. This differs from other NAAQS in that it uses a rolling period, so a new three-month period is calculated with each successive month (e.g., January-March, February-April, etc.).
One feature of Lakes Software applications that our users have come to appreciate, is the wealth of customization options available to provide high quality visualization of model output. Beyond the usual drawing tools for adding model objects, each application contains a set of Annotation Tools which allow users to add additional objects to the main display.
As we described in a previous Modeling Tip, the Ontario Ministry of the Environment, Conservation and Parks (MECP) now distributes Canadian Digital Elevation Model (CDEM) data in GeoTIFF format via a portal on their website.
AERSURFACE is a tool developed by the U.S. Environmental Protection Agency (USEPA) which uses digital land cover data to objectively calculate numeric values of surface characteristics (i.e. albedo, Bowen ratio, and surface roughness) required by AERMET, the meteorological preprocessor for the AERMOD air dispersion model.
Dispersion within urban environments has different characteristics than that occurring in a rural environment. The urban boundary layer will behave in a more convective, turbulent manner during the hours just after sunset due to the urban heat island effect. AERMOD has capabilities to model this boundary layer by enabling the urban dispersion coefficient.