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

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1  1.0 Introduction and Purpose  The purpose of this Final Report is to document the research findings and results of ACRP 02-43 Research Project: Development of a NOx Chemistry Module for EDMS/AEDT to Predict NO2 Concentrations. This report provides the ultimate users of the 02-43 outcomes the necessary information and means for employing a module (i.e., the Preferred Method) for predicting NO2 concentrations resulting from airport emissions and using FAA’s EDMS/AEDT models. The impetus, or need, for this work stems from the concern that existing methods available for predicting NO2 concentrations at airports are too conservative. In this sense (and throughout this report), the term “conservative” means predictions are so high as to be beyond the reasonable range of accuracy. The following sections contain background and summary materials that are specifically aimed at accomplishing the task of developing a Preferred Method that will improve the NO2 concentration predictions for airports. 1.1 Research Objectives  The ACRP 02-43 Project Panel (i.e., Project Panel) identified the three following primary end-products for this Research Project: (i.) a Final Report entitled Development of NOx Chemistry Module for EDMS/AEDT to Predict NO2 Concentrations, (ii.) a Preferred Method and (iii.) a computer model code for the Preferred Method. Together, these are intended to help to ensure that the underlying mechanics and predictive accuracies of EDMS/AEDT and AERMOD (or alternatives to these models) are appropriate and as accurate as possible. 1.2 Research Program  The ACRP 02-43 research was subdivided into 13 tasks, as shown in the flow chart on the next page and summarized below. (These tasks were developed by the Panel and organized in the sequence shown.)  Task 1, Regulations & Standards - The primary aim of this task was to compile and evaluate regulatory- based information pertaining to the 1-hour NO2 NAAQS. Section 3 of Appendix A provides a summary.  Task  2,  Current  Understanding  &  Research  Gaps - This task described the current understanding and research gaps relative to measuring and predicting NO2 concentrations in airport environments.  Task  3,  NOx  Speciation  Methods - Under this task, the Research Team analyzed and evaluated how emissions and chemistry of NOx are accounted for in various NOx speciation methods in EDMS/AEDT/AERMOD.  Task 4, Working Paper – A working paper was prepared to summarize the research and findings from Tasks 1-3.  Task 5, Compare Emission Factors  to Measured Values - This work involved a comparison of NO/NO2 emissions factors used in EDMS/AEDT to available published measurements of NO and NO2 in aircraft engine exhaust at airports. ACRP 02‐43 Objectives   Assess the accuracy of the NOx emissions and speciation methods used in FAA’s EDMS/AEDT  models  and  the  U.S.  EPA  AERMOD  model  to  predict  NO2 concentrations near airports;  Develop  and  assess  alternative methods  (including  at  least one  involving  the NO, NO2, and O3 “photostationary state”; and  From among  the alternative methods evaluated, produce a Preferred Method for predicting NO2 concentrations resulting from airport emissions.

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