The Medical Implications of Nuclear War (1986) / Chapter Skim
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6 Atmospheric Perturbations of Large-Scale Nuclear War
6 Atmospheric Perturbations of Large-Scale Nuclear War
Pages 141-154
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From page 141... ...
All figures are reprinted from Malone, R C., et al., 1986, Nuclear winter: threedimensional simulations including interactive transport, scavenging, and solar heating of smoke, J
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From page 142... ...
This continuing heat loss to space combined with reduced incoming sunlight causes the surface to cool. This is the origin of the so-called nuclear winter effect.
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From page 143... ...
The first of these perturbations is a major change in the atmospheric circulation patterns that causes the heated air and the entrained smoke particles to rise. This carries some smoke particles well above the altitudes to which they were injected initially by the fires.
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From page 144... ...
The sensitivity of smoke transport and removal to the assumed initial vertical distribution of smoke was considered by using two profiles: a low injection with smoke distributed between 2- and 5-km altitude in the lower troposphere, and an NAS injection (so-called because of its use in the study done by the National Academy of Sciences) with constant smoke mass density between the surface and a 9-km altitude (NAS, 1985)
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From page 145... ...
One calculation was done with interactive smoke; the results from it are shown with solid contours. The second calculation was done with a passive tracer; its results 30 25 20 it, 15 10 5 to ' 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 DAY 20 _ rlO .1,: ~ UP 60 30 ED -30 -60 SP LA TITUDE 10 20 30 _` ~2 50 70 100 ~ CO 200 300 500 700 1000 FIGURE 2 Longitudinally averaged mass mixing ratios for July conditions at day 20.
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From page 146... ...
Since precipitation is the primary removal mechanism for smoke, this is where smoke removal will take place. Figure 3B also displays the longitudinally averaged temperature for July conditions, but with the atmosphere being perturbed by the injection of 170 Tg of smoke.
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From page 147... ...
NP 60 30 ED -30 -60 SP 20 30 ._` 50 `§ 70 100 200 300 500 700 1000 ~70 \ _ 330~ ) - t' -- -4270~q o 30 ED -30 -60 SP LA TITUDE 20 30 ~ 50 `§ 70 100 ~ co co 200 300 500 700 1000 FIGURE 3 The longitudinally averaged temperature (degrees Kelvin)
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From page 148... ...
The upper four curves apply to interactive smoke calculations with vertical injection profiles, as indicated, while the lower pair of curves apply to passive tracer calculations with low injection profiles. The vertical axis has a logarithmic scale.
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From page 149... ...
...~/////////5~////~ .. : : : : At/ / / / / 7 / / ~ -~d~ UP 60 30 ED -30 -60 so LA TITUDE 10 20 30 _ 50 70 100 ~ CO 200 300 500 700 1000 FIGURE 4 The relative positions of the modified tropopause (heavy dashed line)
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From page 150... ...
Smoke is removed faster in January than in July simply because there is less sunlight in the Northern Hemisphere to drive the atmospheric perturbations that enhance the lifetime of smoke. By the end of six weeks in our January calculations, the remaining fraction of smoke injected with the low and NAS profiles is about 5 and 15 percent, respectively, compared with 35 percent in the July cases.
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From page 151... ...
. I 0 30 60 90 120 150 180 FIGURE 6 The vertically integrated solar absorption optical depth of smoke at day 20 (A)
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From page 152... ...
A very small amount of smoke has little impact on the atmosphere, which allows the smoke to be quickly removed from the troposphere, much like the passive tracer results in Figures 2 and 5. As the injected mass is increased in the simulations into the range estimated for a major nuclear exchange, the solar heating of smoke and the atmospheric perturbations increase in magnitude.
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From page 153... ...
Values are indicated at the bottom of the figure; the designation <-15 refers to temperature reductions below normal in excess of 15°C. Note that the warm and cool regions near Antarctica are simply manifestations of storms which occur naturally in the wintertime circumpolar flow; they have no connection with the changes occurring in the Northern Hemisphere.
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From page 154... ...
:1039-1053. National Academy of Sciences, Committee on the Atmospheric Effects of Nuclear Explo sions.
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