Rethinking the Ozone Problem in Urban and Regional Air Pollution (1991) / Chapter Skim
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13 Tropospheric Ozone and Global Change
13 Tropospheric Ozone and Global Change
Pages 413-424
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From page 413... ...
. Discussions in this chapter must be mostly qualitative, because few examples of research couple global changes with air quality.
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From page 414... ...
These gases act as greenhouse gases that contribute to the radiative forcing of the atmosphere, increasing the radiative forcing at the tropopause by about 0.5 watts/meter2 over the past decade. The record of global mean surface temperature exhibits fluctuations, but with an apparent increasing trend (Figure 13-1~.
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From page 415... ...
Ozone losses in the northern midlatitudes have been less dramatic but still important as much as 8% over the past decade in winter, with smaller but significant losses in summer (Stolarski et al., 19914. Increases in CH4 and CO, along with other photochemically active trace gases such as odd-nitrogen compounds and volatile organic compounds (VOCs)
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From page 416... ...
Accordingly, qualitative estimates of some of the trends in temperature and trace gases that might be expected over the next two decades are presented. Mechanisms by which these global changes are likely to perturb tropospheric oxidants and local air quality are discussed, but in some cases even the direction (increase or decrease)
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From page 417... ...
The effect of increased ultraviolet light on tropospheric ozone formation depends on NOX concentrations and other conditions that vary with latitude (Liu and Trainer, 1988; Gery et al., 1988b; Derwent, 1989~. Enhanced photochemical activity in the troposphere will lead to increased production of ozone over most continental regions of the northern hemisphere, but can lead to reductions of ozone in clean maritime conditions where photochemistry is a net sink for ozone (Liu and Trainer, 1988; Schnell et al., 1991~.
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From page 418... ...
. regions; c ecrease in remote global areas Unknown; possible increase Increase (local and global)
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From page 419... ...
The feedback relationship between global air quality and local air quality could become more important in the future. The abundance of global OH determines the global oxidative capacity of the lower atmosphere.
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From page 420... ...
Regional air quality will not respond directly to changes in global OH, but the background abundances of biogenic VOCs may be altered and regional ozone thus affected (Chameides et al., 1988; Cardelino and Chameides, 19904.
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From page 421... ...
In particular, the distributions of NOx and reactive VOCs are patchy and likely to be correlated; much of the net production of ozone will come from the highly perturbed regions and will not be related to the longitudinally averaged concentrations. High-resolution regional three dimensional CTMs for tropospheric ozone have been developed in response to the need to study air pollution as discussed in Chapters 9 and 10 and elsewhere (McRae and Seinfeld, 1983; Liu et al., 1984; Carmichael et al., 1986; Chang et al., 1987; McKeen et al., 1990~.
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From page 422... ...
Some global two-dimensional, zonally averaged models for tropospheric ozone use realistic photochemical schemes but, by their nature, fail to resolve the continent-ocean differences in surface emissions and zonal transport (Isaksen and Hov, 1987; Hough and Derwent, 1990~. Consequently, these models fail to account for the nonlinear dependence of ozone production on NOX concentrations.
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From page 423... ...
A major limitation of these models is that they do not properly account for the nonlinear dependence of tropospheric chemistry on NOx and VOC concentrations. SUMMARY The effect of global changes in the climate and atmospheric chemistry on tropospheric ozone are currently unpredictable, but they could lead to substantial increases in the number and duration of pollution episodes and in the size of the regions affected by high oxidant production.
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From page 424... ...
. For comply, it ~ be Ports to continue to Dunlop ~ Remit transport models (amps)
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