Impact of aircraft emissions on reactive nitrogen over the North Atlantic Flight Corridor region

Citation
M. Koike et al., Impact of aircraft emissions on reactive nitrogen over the North Atlantic Flight Corridor region, J GEO RES-A, 105(D3), 2000, pp. 3665-3677
Citations number
28
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Volume
105
Issue
D3
Year of publication
2000
Pages
3665 - 3677
Database
ISI
SICI code
Abstract
The impact of aircraft emissions on reactive nitrogen in the upper troposph ere (UT) and lowermost stratosphere (LS) was estimated using the NOy-O-3 co rrelation obtained during the Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX) carried out over the U.S. continent and North Atl antic Flight Corridor (NAFC) region in October and November 1997. To evalua te the large-scale impact, we made a reference NOy-O-3 relationship in air masses, upon which aircraft emissions were considered to have little impact . For this purpose, the integrated input of NO, from aircraft into an air m ass along a 10-day back trajectory (Delta NOy) was calculated based on the Abatement of Nuisance Caused by Air Traffic/European Commission (ANCAT/EC2) emission inventory. The excess NOy (dNO(y)) was calculated from the observ ed NO, and the reference NOy-O-3 relationship. As a result, a weak positive correlation was found between the dNO(y) and Delta NOy and dNO(y) and NOx/ NOy values, while no positive correlation between the dNO(y) and CO values was found suggesting that dNO(y) values can be used as a measure of the NOx input from aircraft emissions. The excess NOy values calculated from anoth er NOy-O-3 reference relationship made using in situ condensation nuclei da ta also agreed with these dNO(y) values, within the uncertainties. At the N AFC region (45 degrees N-60 degrees N) the median value of dNO(y) in the tr oposphere increased with altitude above 9 km and reached 70 parts per trill ion by volume (pptv) (20% of NOy) at 11 km. The excess NOx was estimated to be about half of the dNO(y) values, corresponding to 30% of the observed N Ox level. Higher dNO(y), values were generally found in air masses where O- 3 = 75-125 ppbv, suggesting a more pronounced effect around the tropopause. The median value of dNO(y) in the stratosphere at the NAFC region at 8.5-1 1.5 km was about 120 pptv. The higher dNO(y) values in the LS were probably due to the accumulated effect of aircraft emissions, given the long reside nce time of affected air in the LS. Similar dNO(y) values were also obtaine d in air masses sampled over the U.S. continent.