Abstract
In this study we 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 O 3 and PM 2.5 concentrations with respect to aviation emissions during landing and takeoff (LTO) cycles at ten individual airports; five located in regions of attainment of O 3 and PM 2.5 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), New York John F. Kennedy (JFK), Los Angeles (LAX), and Charlotte- Douglas (CLT). We utilize these coefficients in an attainment/nonattainment emission decrease/increase analysis to determine the importance of including second order sensitivity coefficients for quantifying O 3 and PM 2.5 concentration responses to LTO aircraft emission reductions near the airport. Sensitivity coefficients help to determine distinct chemical regimes, NO X -limited versus NO X -inhibited for the case of O 3 formation, and NH 3 -rich versus NH 3 -poor for the case of PM 2.5 formation. Overall, we find that NO X LTO emissions are the largest contributor to any potential nonlinearity in O 3 and PM 2.5 formation through LTO emissions. However, when utilizing Taylor series expansions to estimate O 3 and PM 2.5 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, we 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. • Sensitivities can help to determine distinct chemical regimes. • Aircraft NOx emissions contribute most to nonlinear chemistry. • Higher order sensitivities not needed for aircraft emission reduction strategies. • Novel approach to determine emissions sector contribution to attainment designations.
Highlights
We focus on ten individual airports; five airports in regions that are currently in attainment of the O3 and PM2.5 National Ambient Air Quality Standards (NAAQS): Boston Logan (BOS), Kansas City (MCI), Raleigh-Durham (RDU), SeattleTacoma (SEA), and Tucson (TUS); and five airports that are in areas of nonattainment of O3 and PM2.5: Chicago O'Hare (ORD), HartsfieldJackson Atlanta (ATL), John F
volatile organic compounds (VOCs) compete for available OH in the atmosphere, the O3 formation pathways can vary based on the emissions of VOCs or nitrogen oxides (NOX) in a region
For the case of aircraft landing and takeoff (LTO) emissions; any HDDM modeling pursuit that aims to capture the effects of LTO emissions on pollutants need not consider second order sensitivities as levels in emission perturbations that are susceptible to nonlinear effects are well outside the range of accuracy in the HDDM framework; and appropriate methods must be used to account for perturbations of that size (Huang et al, 2017; Yarwood et al, 2013)
Summary
Nonlinear chemistry governs the formation of tropospheric ozone (Sillman, 1995; Tonnesen and Dennis, 2000; Sillman, 2002; Cohan et al, 2005; Xing et al, 2011; Kim et al, 2017; Sharma et al, 2017), and secondarily formed particulate matter (Blanchard et al, 2000; Pun and Seigneur, 2001; Pinder et al, 2007; Dennis et al, 2008; Blanchard and Tanenbaum, 2008; Clappier et al, 2017). The nonlinear chemistry involves the interactions and subsequent availabilities of directly emitted gases and particles in polluted or relatively clean areas. Sensitivity regimes can extend to PM formation with NOX and VOCs as well as other gas and particle species such as sulfur oxides, ammonia, and primary organics adding to the roles of precursors. All of these precursors and the chemical/meteorological impacts of an area will lead to the formation or destruction of O3 and PM.
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