Aviation impact on air quality present day and mid-century simulated in the Community Atmosphere Model (CAM).

Abstract The projected increase in global air traffic raises concerns about the potential impact aviation emissions have on climate and air quality. Previous studies have shown that aircraft non-landing and take-off (non-LTO) emissions (emitted above 1 km) can affect surface air quality by increasing concentrations of ozone (O 3) and fine particles (PM 2.5). Here, we examine the global impacts of aviation non-LTO emissions on surface air quality for present day and mid-century (2050) using the Community Atmosphere Model with Chemistry, version 5 (CAM5). An important update in CAM5 over previous versions is the modal aerosol module (MAM), which provides a more accurate aerosol representation. Additionally we evaluate of the aviation impact at mid-century with two fuel scenarios, a fossil fuel (SC1) and a biofuel (Alt). Monthly-mean results from the present day simulations show a northern hemisphere (NH) mean surface O 3 increase of 1.3 ppb (2.7% of the background) and a NH maximum surface PM 2.5 increase of 1.4 μg/m3 in January. Mid-century simulations show slightly greater surface O 3 increases (mean of 1.9 ppb (4.2%) for both scenarios) and greater PM 2.5 increases (maximum of 3.5 μg/m3 for SC1 and 2.2 μg/m3 for Alt). While these perturbations do not significantly increase the frequency of extreme air quality events (increase is less than 1.5%), they do contribute to the background concentrations of O 3 and PM 2.5 , making it easier for urban areas to surpass these standards. Highlights • We examine the global impacts of aviation non-LTO emissions on surface air quality for present day and mid-century (2050). • The mid-century simulations used two different fuel scenarios, a fossil fuel scenario and a biofuel scenario. • Aviation-induced perturbations in near-surface ozone and PM 2.5 do not significantly increase the frequency of extreme air quality events (increase is less than 1.5%). [ABSTRACT FROM AUTHOR]