Spatial impact of perturbed temperature on peak ozone concentrations

The spatial differences in emission distributions over the entire South Texas region have been summarized in Table 1. Although the peak ozone concentrations declined substantially in the South Texas region compared to the base case, the temperature perturbations radically impact future ozone concentrations. It was found that a 6°C perturbation produces the largest increase of ~12 ppb from the unperturbed case over the San Antonio region and the counties bordering Houston-Galveston area. Austin exhibited an increase of 9-12 ppb, as shown in Fig. 3. Corpus Christi revealed a maximum

Fig. 3. Spatial distribution of the differences in episode maxima concentrations between the base case and the perturbed temperature (6°
Table 2. Maximum impact of perturbed temperature.

+2°C

+3° C

+4°C

+5° C

+6° C

Difference in 8-h ozone conc. in ppb 6.98

8.71

10.13

11.45

12.59

impact of around 10 ppb. The spatial distribution pattern of the differences in the 8-h ozone episodic maxima between the base and the perturbed cases remains similar for all other perturbed temperature scenarios with the greatest impact occurring downwind of urban regions and particularly downwind of Houston-Galveston area. The utmost impact on the peak 8-h ozone concentrations is an increment of ~1.5 ppb from the preceding perturbed temperature case, as shown in Table 2 with the differences getting smaller for higher temperature perturbations.

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