Koike, M.Kondo, Y.Ikeda, H.Gregory, G. L.Anderson, B. E.Sachse, G. W.Blake, D. R.Liu, S. C.Singh, H. B.Thompson, Anne M.Kita, K.Zhao, Y.Sugita, T.Shetter, R. E.Toriyama, N.2024-07-262024-07-262000-02-01Koike, M., Y. Kondo, H. Ikeda, G. L. Gregory, B. E. Anderson, G. W. Sachse, D. R. Blake, et al. “Impact of Aircraft Emissions on Reactive Nitrogen over the North Atlantic Flight Corridor Region.” Journal of Geophysical Research: Atmospheres 105, no. D3 (2000): 3665–77. https://doi.org/10.1029/1999JD901013.https://doi.org/10.1029/1999JD901013http://hdl.handle.net/11603/34940The impact of aircraft emissions on reactive nitrogen in the upper troposphere (UT) and lowermost stratosphere (LS) was estimated using the NOᵧ-O₃ correlation obtained during the Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) carried out over the U.S. continent and North Atlantic Flight Corridor (NAFC) region in October and November 1997. To evaluate the large-scale impact, we made a reference NOᵧ-O₃ relationship in air masses, upon which aircraft emissions were considered to have little impact. For this purpose, the integrated input of NOₓ from aircraft into an air mass along a 10-day back trajectory (ΔNOᵧ) was calculated based on the Abatement of Nuisance Caused by Air Traffic/European Commission (ANCAT/EC2) emission inventory. The excess NOᵧ (dNOᵧ) was calculated from the observed NOᵧ and the reference NOᵧ-O₃ relationship. As a result, a weak positive correlation was found between the dNOᵧ and ΔNOᵧ, and dNOᵧ and NOₓ/NOᵧ values, while no positive correlation between the dNOᵧ and CO values was found, suggesting that dNOᵧ values can be used as a measure of the NOₓ input from aircraft emissions. The excess NOᵧ values calculated from another NOᵧ-O₃ reference relationship made using in situ condensation nuclei data also agreed with these dNOᵧ values, within the uncertainties. At the NAFC region (45°N–60°N) the median value of dNOᵧ in the troposphere increased with altitude above 9 km and reached 70 parts per trillion by volume (pptv) (20% of NOᵧ) at 11 km. The excess NOₓ was estimated to be about half of the dNOᵧ values, corresponding to 30% of the observed NOₓ level. Higher dNOᵧ values were generally found in air masses where O₃ = 75–125 ppbv, suggesting a more pronounced effect around the tropopause. The median value of dNOᵧ in the stratosphere at the NAFC region at 8.5–11.5 km was about 120 pptv. The higher dNOᵧ values in the LS were probably due to the accumulated effect of aircraft emissions, given the long residence time of affected air in the LS. Similar dNOᵧ values were also obtained in air masses sampled over the U.S. continent.13 pagesen-USThis work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.Public DomainText