Geoscience Reference
In-Depth Information
There has been little focus so far on the effect of temperature perturb-
ations on regional and urban ozone quality in the South Texas region.
Emission control policies in these parts are currently implemented assuming
that the climate conditions remain constant. This study illustrates the
significant impact climate changes can have on potential ozone concentra-
tions in the future, despite the assimilation of substantial emission red-
uction procedures. It examines the impact of an array of temperature
perturbations on the model-simulated 8-h averaged ozone concentrations
for the 2007 future case where emissions and other meteorological para-
meters were held constant. This study provides an in-depth analysis of
the importance of the role of possible climate variability on surface
ozone concentrations in South Texas by investigating spatial and temporal
responses in modeled peak surface ozone concentrations and ozone
exceedances to various temperature perturbations. The promulgation of
a longer-term 8-h ozone standards since 1997 based on more rigorous
health assessments by the USEPA resulted in an overall increase of non-
attainment areas. Spatial and temporal scales are intrinsically linked in the
ozone process as mentioned by Rao
.
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Therefore, the possible lowering
of federal ozone standards to 70-75 ppb in the future
10
will considerably
enhance this problem. This issue of climate change then becomes even more
critical if the 8-h standards become more stringent in the near future, and
this is highlighted in the study described here.
The primary objective of this ozone sensitivity study is to enhance the
awareness of decision-makers regarding climate change impact on surface
ozone concentrations so that future potential emission abatement strategies
may be developed, factoring climate change in the decision-making process
for the South Texas region.
et al
2. Model Description
The Comprehensive Air quality Model with extensions (CAMx) version
3.1,
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has been applied to assess the impact of perturbed temperatures in
the South Texas region. The photochemical model CAMx that simulates
various atmospheric physical and chemical processes was applied in a nested
grid mode in this study. The base case modeling simulations were performed
for high ozone days of 13-20 September 1999 that occurred in South Texas.
The future case modeling simulations were conducted for 2007 projected to
have a similar set of episodic days. Meteorological fields, boundary and
