Geoscience Reference
In-Depth Information
IMPACT ASSESSMENT OF GLOBAL TEMPERATURE
PERTURBATIONS ON URBAN AND REGIONAL
OZONE LEVELS IN SOUTH TEXAS
JHUMOOR BISWAS, KURUVILLA JOHN and ZUBER FAROOQUI
CREST-RESSACA, Frank H. Dotterweich College of Engineering,
Texas A&M University-Kingsville, Kingsville, Texas 78363
The recent Intergovernmental Panel on Climate Change report predicts signifi-
cant temperature increases over the century which constitutes the pulse of cli-
mate variability in a region. A modeling study was performed to identify the
potential impact of temperature perturbations on tropospheric ozone concen-
trations in South Texas. A future case modeling scenario which incorporates
appropriate emission reduction strategies without accounting for climatic
inconsistencies was used in this study. The photochemical modeling was
undertaken for a high ozone episode of 13-20 September 1999, and a future
modeling scenario was projected for ozone episode days in 2007 utilizing
the meteorological conditions prevalent in the base year. The temperatures
were increased uniformly throughout the simulation domain and through
the vertical layers by 2
◦
C, 3
◦
C, 4
◦
C, 5
◦
C, and 6
◦
C, respectively in the
future year modeling case. These temperature perturbations represented the
outcome of extreme climate change within the study region. Significantly large
changes in peak ozone concentrations were predicted by the photochemical
model. For the 6
◦
C temperature perturbation, the greatest amplification in
the maximum 8-h ozone concentrations within urban areas of the modeling
domain was approximately 12 ppb. In addition, transboundary flux from major
industrialized urban areas played a major role in supplementing the high ozone
concentrations during the perturbed temperature scenarios. The Unites States
Environmental Protection Agency (USEPA) is currently proposing stricter 8-h
ozone standards. The effect of temperature perturbations on ozone exceedances
based on current and potential stringent future National Ambient Air Quality
Standards (NAAQS) was also studied. Temperatures had an appreciable spatial
impact on the 8-h ozone exceedances with a considerable increase in spatial area
exceeding the NAAQS for the 8-h ozone levels within the study region for each
successive augmentation in temperature. The number of exceedances of the
8-h ozone standard increased significantly with each degree rise of temperature
with the problem becoming even more acute in light of stricter future proposed
standards of ozone.
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