United States Department of Transportation
i
Assessing the Importance of Nonlinearity for Aircraft Emissions’ Impact on O₃ and PM₂.₅
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2021-03-01
[PDF-5.44 MB]
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Edition:Journal Article
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Abstract:In this study the authors utilize the Decoupled Direct Method (HDDM-3D) as implemented in the Community Multiscale Air Quality Model (CMAQ) to calculate first and second order sensitivity coefficients of O₃ and PM₂.₅ concentrations with respect to aviation emissions during landing and takeoff (LTO) cycles at ten individual airports; five located in regions of attainment of O₃ and PM₂.₅ NAAQS: Boston Logan (BOS), Kansas City (MCI), Raleigh-Durham (RDU), Seattle-Tacoma (SEA), and Tucson (TUS); and five airports in current nonattainment areas: Chicago O’Hare (ORD), Hartsfield- Jackson Atlanta (ATL), John F. Kennedy (JFK), Los Angeles (LAX), and Charlotte- Douglas (CLT). The authors utilize these coefficients in an attainment/nonattainment emission decrease/increase analysis to determine the importance of including second order sensitivity coefficients for quantifying O₃ and PM₂.₅ concentration responses to LTO aircraft emission reductions near the airport. Sensitivity coefficients help to determine distinct chemical regimes, NOₓ-limited versus NOₓ-inhibited for the case of O₃ formation, and NH₃-rich versus NH₃-poor for the case of PM₂.₅ formation. Overall, the authors find that NOₓ LTO emissions are the largest contributor to any potential nonlinearity in O₃ and PM₂.₅ formation through LTO emissions. However, when utilizing Taylor series expansions to estimate O₃ and PM₂.₅ concentration responses under LTO emission perturbation scenarios, differences in responses calculated using only first order coefficients and responses calculated using both first and second order coefficients were less than 1% for LTO emission perturbations less than 100%. Hence, the authors find from the results in this study that first order sensitivity coefficients are sufficient for constructing accurate LTO emissions perturbation scenarios. This study also demonstrates through the analyses performed, an illustration of how HDDM-based sensitivity calculations can be used to assess sector-specific impacts on attainment designations.
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Content Notes:This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/4.0/).
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