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the number of exceedances in certain grid cells in the modeling domain located
mostly within the urban regions.
As shown in Table 6, San Antonio NNA region is the most affected
area amongst the NNAs with 18 8-h ozone exceedances in the base case.
Corpus Christi and Austin do not possess any 8-h ozone exceedances in the
base case, but the number of ozone exceedances in these areas increases
significantly with every 1
◦
C rise in temperature above 3
◦
C. In the case of
San Antonio, the consequent increase in the number of exceedances with
the rise of temperature is not as substantial as that observed in Austin
especially for exceedances greater than 74 ppb. This analysis also indicates
that ozone exceedances greater than 74 ppb occur in both large and small
urban regions resulting in considerable increase in the number of ozone
exceedances throughout the study region in Texas.
5. Conclusion
An assortment of ozone sensitivity runs were completed with different
perturbations in temperatures over south Texas for a future year simulation
using the high ozone days of September 1999. The results categorically
revealed that global temperature augmentations could significantly impact
peak 8-h ozone concentrations and 8-h ozone exceedances especially in the
urban regions of south Texas. Climate interactions play an increasingly
important role in local and regional air quality background concentrations.
Transboundary flux enhancements also supplement ozone concentrations in
the perturbed temperature scenarios. These results prove conclusively that
potential emission control strategies need to incorporate climate change
in their formulation. Climate change can amplify pollution-related health
effects due to increase in the number of ozone exceedances. This issue of
climate change becomes even more crucial if the 8-h standards become more
stringent in the future. The lowering of ozone standards will substantially
enhance the number of instances of ozone exceedances as well as the
area under non-attainment of the 8-h ozone standards with increased
temperature perturbations.
Acknowledgments
This material is based upon the work supported by the Center for Research
Excellence in Science and Technology — Research on Environmental
Sustainability of Semiarid coastal arid (CREST-RESSACA) at Texas
