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Info box: "Aircraft induced NOx"

Keywords:
  • Aircraft
  • Nitrogen oxide
  • UTLS
  • Short lifetime
  • Seasonal cicle
  • Steady state
 Input parameter:
  • Lifetime: 8d
  • Emission rate: .5 - 1e9 molecules cm**-2 s**-1
  • Emission source:
    • Process: Subsonic civil aircraft
    • Geographical distribution:
      Mainly Europe, North America, and the "flight corridor" in between
    • Altitude: 200hPa ~ 12km
  • Start distribution: Zero
  • Simulation time: 37 month
Vocabulary: Model results:
  • Concentrations:
    ~ 60 - 100 pptv in the flight corridor
    almost zero at the earth's surface
  • Spatial variability:
    High gradients around the emission sources
  • Steady state:
    Reached after one month: Feb. 2001 looks like Feb. 2000.
    However Jan. 2001 is obviously different from Jan. 2000, but equal to Jan. 2002 and 2003.
  • Seasonality:
    Very well pronounced in the source region.
    The seasonal maxima built up in May - minima in January and October.
  • Conclusion:
    Short lifetime of a species results in high spatial variability and a rapid levelling into steady state.
  • Other remarks:
    The chemistry of NOx is not included in this simple exercise. Thus the chemical lifetime is exclusively defined by the prescribed parameter which neither varies with time nor with altitude. This is a simplifying assumption and only approximately realistic. The photochemistry of NOx is driven by solar radiation, the intensity of which depends on the season (zenit angle) the day/ night cycle and also on cloud cover.
    However, the goal of the exercise is to demonstrate where aircraft-NOx emissions can pollute the atmosphere and how far they can "travel" under the conditions defined above.