Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
variability in the troposphere places severe constraints on the atmospheric sampling strategy one would have to adopt to collect representative data.
In principle, aircraft signatures could be discerned from observation of the distribution of NOx because the aircraft source is geographically distinct. In situ aircraft
sampling efforts have begun to provide a global map of NOx in the UT (Emmons et al., 1997; see also Figure 2-6a). During the past few years, field campaigns have
been performed specifically to investigate aircraft flight corridors. For example, observations in air traffic have been made by Schlager et al. (1996, 1997). The
observation area was the major flight route in the eastern North Atlantic, and the parameters observed were NOx , SO2 , and particles; observations were made
perpendicular to flight tracks. Under special meteorological conditions associated with a stagnant anticyclone, measured data indicated a large-scale accumulation of
NO x and particles from aircraft emissions.
Approximately 4,000 hours of NO x measurements were collected from a B-747 platform during the Nitrogen Oxides and ozone measurements along Air Routes
(NO x AR) project between spring 1995 and spring 1996, as shown in Figure 2-6b (Brunner, 1998). The NO x AR measurements demonstrated that, in addition to aircraft
emissions, NO x produced by lightning and NO x emitted at the surface and transported upward by convection make large contributions to the NO x abundance in the
UT. These contributions were largest over and downstream of continents in summer. Finally, the recently completed SONEX and POLINAT II campaigns were
designed specifically to quantify various NO x sources in the UT. The findings of these latest studies are just now being reported.
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