Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
Aviation and the Global Atmosphere
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9.3.4. Comparisons of Present-Day and 2015 Forecast Emissions Inventories (NASA, ANCAT/EC2, and DLR)
Other reports in this collection
Table 9-4 lists the totals for calculated fuel burned and emissions from the NASA, ANCAT, and DLR inventories for 1976, 1984, 1992, and 2015. Because these
inventories consisted of 3-D data sets, the differences in spatial distributions as well as totals are compared. The NASA inventories also included emissions of CO and
HC, which are summarized in Table 9-5.
The NASA inventories include piston-powered aircraft in the general aviation fleet. This category of aircraft is excluded from the ANCAT and DLR inventories, but the
contribution to total fuel burned from these aircraft is small (2.6% of fuel burned in 1992). Piston-powered aircraft are large contributors to CO and HC emissions
relative to the amount of fuel they burn (39% of CO and 13% of HC emissions in 1992). This large relative contribution is reflected in the emissions indices of these two
pollutants in the general aviation category.
A comparison of calculated global total values for fuel burned and NO x emissions from the
NASA, ANCAT, and DLR inventories for 1992 and 2015 is shown in Figure 9-9. All three
inventories for 1992 have approximately the same calculated values for total fuel burned in the
civil air fleet; the difference in total fuel (7% maximum) arises almost entirely from different
calculated contributions for military aviation operations, for which the ANCAT inventory
calculates 33% lower fuel burned. Because military fuel is estimated to be between 13 and 18%
of total fuel in 1992, the effect of this large difference in estimates between military sectors on
the total is small. Use of the NASA inventories as a base is arbitrary and does not imply that
differences from the NASA results are errors. Exclusion of turboprop operations from the ANCAT
inventory results in about a 2% underestimate (if data from the NASA inventory are used).
Calculated values for total NO x emissions from the three inventories for 1992 are within 9% of
each other. The ANCAT and DLR values are higher than those from NASA-a result of a
combination of differing fleet mixes, a different method of calculating NO x emissions, and the
offsetting effects of civil and military calculations. This variation is also reflected in the calculated
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