Impact from emitted NO(sub x) and VOC in an aircraft plume. Model results for the free troposphere

摘要

The chemical fate of gaseous species in a specific aircraft plume is investigated using an expanding box model. The model treats the gas phase chemical reactions in detail, while other parameters are subject to a high degree of simplification. Model simulations were carried out in a plume up to an age of three days. The role of emitted VOC, NO(sub x) and CO as well as of background concentrations of VOC, NO(sub x) and ozone on aircraft plume chemistry was investigated. Background concentrations were varied in a span of measured values in the free troposphere. High background concentrations of VOC were found to double the average plume production of ozone and organic nitrates. In a high NO(sub x) environment the plume production of ozone and organic nitrates decreased by around 50%. The production of nitric acid was found to be less sensitive to background concentrations of VOC, and increased by up to 50% in a high NO(sub x) environment. Mainly, emitted NO(sub x) caused the plume production of ozone, nitric acid and organic nitrates. The ozone production during the first hours is determined by the relative amount of NO(sub 2) in the NO(sub x) emissions. The impact from emitted VOC was in relative values up to 20% of the ozone production and 65% of the production of organic nitrates. The strongest relative influence from VOC was found in an environment characterized by low VOC and high NO(sub x) background concentrations, where the absolute peak production was lower than in the other scenarios. The effect from emitting VOC and NO(sub x) at the same time added around 5% for ozone, 15% for nitric acid and 10% for organic nitrates to the plume production caused by NO(sub x) and VOC when emitted separately 47 refs, 15 figs, 4 tabs