Geoscience Reference
In-Depth Information
Table 4.
Number of grid cells exceeding 84 ppb.
Perturbed temperature
Future case
+2
◦
C+
◦
C+
◦
C+
◦
C+
◦
C
Austin
0
0
10
39
63
97
San Antonio
10
44
60
74
88
103
Corpus Christi
0
0
1
12
19
35
Victoria
0
0
0
0
0
0
Entire domain
10
63
98
161
247
409
Table 5.
Number of grid cells exceeding 74 ppb.
Perturbed temperature
+2
◦
C+
◦
C+
◦
C+
◦
C+
◦
C
Future case
Austin
76
331
480
564
630
687
San Antonio
113
195
210
225
236
257
Corpus Christi
48
109
132
149
165
182
Victoria
0
37
93
126
134
146
Entire domain
430
1570
2220
2751
3150
3466
in the future case. Austin, Corpus Christi, and Victoria NNA regions have
no instances of ozone exceedances in this case. However, Austin and Corpus
Christi regions reveal a significant increase in the number of grid cells with
ozone exceedances for the 4
◦
C-6
◦
C temperature perturbation cases relative
to the unperturbed case. Overall, the inland areas show a much greater
impact with increasing temperature perturbations than the coastal regions
which is also consistent with the base case results.
Table 5 shows that in the event the standards are lowered in the
future to 74 ppb, and that the pattern of potential spatial representation
of exceedances in the future also changes. Austin will now have a greater
spatial extent of exceedance values compared to San Antonio with increasing
temperature perturbations. In the unperturbed case, although San Antonio
still possesses the largest number of grid cells exceeding the standards with
rising temperature perturbations, Austin has the largest percent of area
affected by ozone exceedances. Lefohn
et al.
18
analyzed that implementation
of controls triggers fastest deterioration of ozone concentrations in those
sites with highest daily maximum 8-h averaged concentrations relative to
other sites. San Antonio seems to have benefited the most in the future
scenario relatively. With the increasing temperature perturbations the ozone
exceedances in the event of a lowered standard is not as extensive in
