Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
Figure 4-2 shows calculated zonal average increases of NO x from aircraft emissions in
July 2015. In the Northern Hemisphere, all but one model calculate increases of up to
150 pptv. These increases can be compared with background levels of 50-200 pptv at
northern mid-latitudes in the 12-km region. In the stratosphere, the ECHAm 3 /CHEM
model calculates larger increases, probably as a result of more efficient transport to the
stratosphere. The height distribution of NO x increases is very similar among models. All
models also predict noticeable increases in upper tropospheric NO x at low latitudes in
the Southern Hemisphere. Only small increases are estimated in the lower troposphere.
Background NO x conditions, however, are rather different in the 3-D CTMs. For
instance, at 12 km at 50°N, calculated background NO x mixing ratios may vary,
depending on the season, by a factor of 2 to 4. Such large differences could be
important for O 3 production because of the nonlinear dependency of net O 3 production
on NOx concentrations, although, for the model scenarios explored, the global O3 increase appears to be almost linear for most of the anticipated NOx injections in the
models (see Figure 4-3).
4.2.3.3. Future Total Ozone Increases from Aircraft Emissions and
Comparison with Increases from Other Sources
Figure 4-3
presents the
increase of
global O3 abundance up
to 16 km from
aircraft
emissions.
The annual
emissions of
0.5, 1.27, and
2.17 Tg N
correspond to
(projected)
emissions for
1992, 2015,
and 2050,
respectively.
Calculated O3 http://www.ipcc.ch/ipccreports/sres/aviation/048.htm (3 von 10)08.05.2008 02:42:21
Figure 4-2: July zonal average increase in NOx [pptv]
from aircraft.