The AERMOD air dispersion model allows users to input time-varying concentration data to represent background sources to be added to the model’s calculations. This can be done by directly adding background concentrations to modeled pollutant concentrations or, in the case of nitrogen dioxide (NO2), by adding background ozone or NOx concentrations to assist in estimating how much NO2 is formed through chemical transformation.
As we have discussed in this space before, presenting high-quality graphical depictions of air dispersion modeling output is vital to communicating the meaning of the calculations. The Graphical Options within Lakes Software’s wide range of commercial products give users the customization options that modelers need.
The AERMOD air dispersion model features many different settings which provide users the ability to customize how model output is presented. Within the model’s Source Pathway are multiple options for grouping sources, but just what do all these different groups mean?
The Plume Volume Molar Ratio Method (PVMRM) is one of several methods built into AERMOD for assessing the conversion of NOX to NO2. Originally developed by Hanrahan as a post-processor for the ISCST3 model, this conversion method is considered a Tier 3 screening method according to the Guideline on Air Quality Models (Appendix W to 40 CFR Part 51).
Numerous versions of the AERMOD model have been released over the years. These updates include new algorithms, enhancements to existing features, bug fixes, and more.
The AERMOD modeling system has a variety of settings and options which can be employed in many ways. This includes options which have been pre-approved for use in regulatory applications and those which are meant for testing or may require additional approval in a regulatory context.