Effects of Meteorology on Air Pollution - Air Pollution and Global Warming: History, Science, and Solutions - page 149

Figure 6.23. Elevated layer of smoke trapped in an inversion layer following a greenhouse fire in Menlo Park,
California, in June 2001. Photo by Mark Z. Jacobson.

Third, emissions from a smokestack or fire can rise
buoyantly into an inversion layer. The inversion lim-
its the height to which the plume can rise and forces
the plume to spread horizontally. Figure 6.23 shows an
example of a pollution layer formed by this mechanism.
Fourth, elevated ozone layers in the boundary layer
may form by the destruction of surface ozone. During
the afternoon, ozone is diluted uniformly throughout
amixing depth. In the evening, cooling of the ground
stabilizes the air near the surface without affecting the
stability aloft. In regions of nighttime NO(g) emissions,
the NO(g) destroys near-surface ozone. Because night-
time air near the surface is stable, ozone aloft does
not mix downward to replenish the lost surface ozone.
Figure 6.24 shows an example of an elevated ozone
layer formed by this process. The next day, the mix-
ing depth increases, recapturing the elevated ozone
and mixing it downward. McElroy and Smith (1992)
estimated that daytime downmixing of elevated ozone
enhanced surface ozone in certain areas of Los Angeles

2000

Aircraft
spiral
-121.24W
37.89N
8/06/90
05:08 PST

1500

1000

500

0

0 0.05 0.1 0.15

Ozone mixing ratio (ppmv)

Figure 6.24. Vertical profile of ozone mixing ratio
over Stockton, California, on August 6, 1990, at 05:08
PST, showing a nighttime elevated ozone layer that
formed by the destruction of surface ozone. Data
from the SARMAP field campaign (Solomon and
Thuillier, 1995).