Atmospheric Effects of Aviation A Review of NASA's Subsonic Assessment Project (1999) / Chapter Skim
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3 Modeling Considerations
3 Modeling Considerations
Pages 27-30
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From page 27... ...
STUDIES WITH EXISTING CHEMICAL-TRANSPORT MODELS Six chemical mechanisms were evaluated for the SASS interim assessment. All the models were initialized with identical upper-tropospheric chemical and meteorological conditions.
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From page 28... ...
The simulation results reported in both documents agree with prior studies in suggesting that aircraft emissions could result in an increase in concentrations of both nitrogen oxides and ozone in the troposphere. The aviation-related NOX increase in the upper troposphere in the latitude band 30 to 60°N is estimated to be as high as 50%, with ozone increases of a few to 10 pptv (Brasseur et al., 1997~.
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From page 29... ...
As noted earlier, the radiative effects of contrail particles may be very different from those of naturally occurring cirrus, because of the different mechanisms by which they are formed. Contributing to the difficulties of representing the effects of aerosols and contrails in 3-D climate models are the uncertainties in portraying natural clouds in GCMs.
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From page 30... ...
They found that the direct radiative perturbations due to water vapor were very small, but that contrails could have a significant effect on climate, with the strongest response occurring under midlatitude summer conditions; however, a number of uncertainties involving cloud radiative interactions make the results somewhat preliminary. These uncertainties make it much more difficult to use standard 3-D climate models (such as those used to evaluate the climate response to increased atmospheric CO2, CH4, N2O, and CFC concentrations)
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