Geoscience Reference
In-Depth Information
Table 2.
Maximum impact of perturbed temperature.
+2
◦
C+
◦
C+
◦
C+
◦
C+
◦
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.
∼
4.3
. Peak ozone impacts at air quality monitoring
sites in south texas
The model-predicted 8-h averaged ozone concentrations were extracted
at the Continuous Air Monitoring Sites (CAMS) maintained by TCEQ
and located in Austin, San Antonio, Victoria, and Corpus Christi. Table 3
illustrates the impact of temperature perturbations on the model-predicted
8-h episodic peak ozone concentrations at each of the CAMS sites for each
NNA subdomain. The 2007 future case exhibits a decline in the peak ozone
concentrations of 5-6 ppb at the monitoring sites from the 1999 base case.
However, with successive temperature perturbations, the peak 8-h ozone
amplifications rise rapidly at the monitoring sites and exceed the base case
ozone concentrations despite curbing of emissions, as shown in Table 3.
This illustrates the importance of accounting for climate change impact
while devising emission control strategies. The San Antonio area exhibits
the highest episodic 8-h ozone concentrations amongst all the CAMS sites
followed by Austin, Victoria, and Corpus Christi. The rate of increase of
peak ozone values declines after the initial perturbation at these sites.
4.4
. Spatial extent of ozone exceedances
Ozone exceedance values are important from the standpoint of health and
hence from a regulatory perspective. Figures 4 and 5 characterize the spatial
pattern of 8-h ozone exceedances greater than 84 ppb and 74 ppb for a
