Development of a NOx Chemistry Module for EDMS/AEDT to Predict NO2 Concentrations (2017)

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56  Additional, but somewhat less analytical, attributes to the Method 1 - Equation 1 recommendation include the following:  Photostationary State - With the exception of the full conversion method, all methods (including Method 1 - Equation 1) take into account (directly or indirectly) the photostationary reactions or the effects thereof.  Computational Requirements - Input data and computational complexities for methods such as those used in CALPUFF and SCICHEM are significant and beyond the scope of most EDMS/AEDT users. By comparison, the Method 1 - Equation 1 approach is simpler and more “user-friendly.”  AERMOD Compatibility - Some methods (e.g., PVMRM & OLM) require close integration with the plume dynamics within AERMOD and may be difficult to modify without altering AERMOD, an action that could render the resulting model package “non-EPA-approved.” Again, the recommended Method 1 - Equation 1 (i.e., ARM2-Airport) for modeling NO2/NOx ratios using the EDMS/AEDT-AERMOD software package meets the Preferred Method “Key” Targets, simply demonstrated as follows: Preferred Method “Key” Targets for ARM2-Airport Module Criteria Meets Criteria Reasonable Data Requirements Yes Practical Computational Requirements Yes Reasonable Accuracy Yes Technically Defensible Yes EDMS/AEDT/AERMOD-Compatible Yes Notably, there may be instances that more sophisticated methods and/or models than ARM2-Airport may be appropriate 7.0 Module Development   As discussed above in Section  1.1, the Research Plan also calls for a computer module that can be applied to EDMS/AEDT for computing NO2/NOx ratios and NO2 concentrations using the Preferred Method. These FAA models are built on a modular architecture where discreet computational modules work in conjunction with a central database to predict air emissions and concentrations (in the case of EDMS) and airport-related noise, air emissions and concentrations (in the case of AEDT). As such, any new methods with the potential to work within this system must be developed as a self-contained module that can be accessed by the system taskmaster software. In summary, the new module would be in the form of a computational library. The FAA designed AEDT under a modular architecture so that each of the computational components (e.g., aircraft performance, fuel burn, emissions, etc.) could be itemized into a callable library. This provides efficiency when making updates to the system, minimizing impacts that one library module may have on another. The modules are typically developed within the Microsoft Visual Studio development environment using ARM2 ‐ Airport Model Module  A Dynamic Link Library (DLL)  module has been developed based  on the recommended Method 1 ‐  Equation 1 for predicting ambient  NO2/NOx ratios. The only input  required by the user is the ambient  NOx concentration, and the  accessible outputs are the NO2/NOx  ratio and the NO2 ambient  concentration at receptor locations.