Ozone calculated temperature profiles

Figure 5. Calculated temperature profiles for unity initial ozone mole fraction (-----), the result of substituting Wamatz s expression for k, and k2 into our model.

Chen et al., 1997). Perhaps most important is the ability of models to simulate the overall shapes of the vertical profiles of the responses obtained in both ozone and temperature, since these in turn support the calculation of the penetration of radiation into the atmosphere and hence provide a key test of theory. 

Calculations of RF due to the growth in tropospheric ozone concentration gave a value of 0.4 0.15 Wm 2. A decrease in total content of ozone in the stratosphere could lead to RF equal to 0.2 0.1Wm"2. Though these changes in sign mutually cancel each other out to a great extent, this does not imply that they are insignificant, since variations of the ozone content in the troposphere and stratosphere aflect substantially—but diflerently—the formation of the temperature vertical profile. 

In order to distinguish which expression for k2, if either, is correct, high temperature measurements and/or ab initio calculations of the rate coefficient for reaction (2) are required. Alternately, the computed differences in the values for atomic oxygen and for the temperature in the burned region at an initial ozone mole fraction of unity appear to be large enough that profile measurements above such a flame may be sufficient to distinguish between the two expressions. 

By means of equation [3.17], the equilibrium vertical profile of the ozone concentration can be calculated. Thus, [02] on the right-hand side is known for various altitudes and k can be calculated for different temperatures.11 The greatest problem is the determination of /, and f2 as a function of altitude. The values of these latter parameters depend on the absorption of radiation, which varies in a complex way as solar radiation penetrates into the atmosphere. Theoretically /, and J2 are calculated by the following two equations ... 

The reduction procedure was applied to three sets of initial conditions which were taken from environmental chamber experiments, 134P, 136P and 137P of Hess et al [6]. Without isoprene this gave initial VOC NOx ratios of 3.5, 8.7 and 15.6 [N C) / A (NOx). The concentrations of the species were simulated for a 48 hour period in which the temperature and solar flux were varied as for a typical diurnal cycle in July at a latitude of 50° N [7]. No further emission or deposition of species were included in the simulation. At each stage of the reduction the ozone profile calculated from the smaller mechanism was compared with that for the CBMEX profile. 

---