Aviation and the Global Atmosphere

Aviation and the Global Atmosphere
Latitude January April July October
65°S 318.8 299.2 (380.0) 312.7
45°S 303.4 286.3 324.3 353.7
30°S 275.7 269.0 290.2 310.1
0° 250.1 260.1 264.9 265.8
30°N 275.3 308.9 294.1 272.5
45°N 352.8 373.0 326.0 295.0
65°N (380.0) 424.3 329.2 304.8
* There are no TOMS measurements for winter at high
latitudes. The values shown in parentheses for winter at 65°S
and N are the values given for winter subarctic columns
in Anderson et al. (1986). The distributions of ozone with altitude
for the columns shown in Table 5-1 are derived
from Park et al. (1999).
The underlying principle for the methodology described below is that calculations of ozone changes derived from chemical transport models should be related to
measurements. For this chapter, calculations designed to determine ozone changes for the present and the future have been related to present-day measurements of
ozone columns and profiles. Model calculations are then used to estimate the impact of aviation in 1970, 1992, 2015, and 2050. The modeled impacts are compared
with other changes that are calculated to have occurred to ozone columns since 1970 and predicted to occur between 1992 and 2050. The radiative transfer
calculations reported in this chapter were performed using a stand-alone version of the solar radiation module from the Commonwealth Scientific and Industrial
Research Organisation (CSIRO) 2-D chemical transport model (CTM), which has been described in Stolarski et al. (1995) and Randeniya et al. (1997). The method of
Meier et al. (1982) is used to account for the effects of multiple scattering, and ray-tracing techniques are used to account for the curvature of the Earth. The CSIRO
radiative transfer model participated in the photolysis benchmark intercomparison conducted as part of the 1995 Atmospheric Effects of Stratospheric Aircraft (AESA)
assessment (Stolarski et al., 1995), and excellent agreement was obtained with the benchmark calculations. Intercomparisons have also been performed with the
Tropospheric Ultraviolet and Visible (TUV) model developed by Madronich using calculations made at the Laboratory of Atmospheric Physics at the University of
Thessaloniki. The radiative transfer equation in TUV was solved by using the discrete ordinate radiative transfer (DISORT) code in 16-stream mode (Stamnes et al.,
1988). Erythemally weighted fluxes were calculated at the ground under clear-sky conditions for zenith angles from 0 to 80°. Using the same input parameters,
agreement was obtained with the CSIRO model to within 2-3% for zenith angles up to 60° and within 5% for a zenith angle of 80°.
5.4.1.1. Ozone Columns and Profiles
The calculations address the effect of aviation on UV at the surface in 1970, 1992, 2015,
and 2050. For the years 2015 and 2050, there will be a range of scenarios that will be
influenced primarily by the expected size and composition of the fleets and the amount and
composition of emissions. In principle, however, the UV calculations require a
representation of a background atmosphere and an atmosphere that includes the effects of
aircraft emissions for each of the years 1970, 1992, 2015, and 2050. The term "background"
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