Regional and intercontinental modelling - Air Pollution Modeling and Its Application - page 190

Acknowledgments This material is based upon work supported by CREST-RESSACA at Texas
A&M University - Kingsville through a Cooperative Agreement No. HRD-0734850 from the
National Science Foundation.

References

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conditions and spatial emission resolutions on the ozone concentration and ROG/NOx
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Emery CA, Tai E, Wilson GM, Yarwood G (2002) Report from ENVIRON International
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Farooqui MZ (2008) Development of a comprehensive air quality modeling framework for a
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Farooqui MZ, John K, Gupta AK (2010) Evaluation of the impact of marine vessels on ambient
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ment (In Press).

6. Questions and Answers

Ronald C. Cohen: Is the observed O 3 decrease on weekends the same as
predicted? Weekend NO x is approximately 25% lower than weekday NO x ,
therefore observations can provide a direct comparison.
Answer: The observed ozone data shows a 2-26% decrease during weekend days
at the monitoring sites possibly due to a decrease in the NO x emissions. The
model also captured this similar trend of decrease in ozone from weekday to
weekend. The total modeled NO x showed a net decrease of less than 10%
during weekend days in the near non-attainment areas of Texas during the high
ozone episode in September 2002. This is also borne out by our findings that
most of the region is NO x limited. However for the high ozone episode of 1999
there is no discernible trend between weekday and weekend ozone concen-
trations even though the NO x emissions reveal a decrease from weekday to
weekend. This demonstrates the importance of meteorology and regional trans-
port for the 1999 ozone episode. This study thus reemphasizes the importance
of considering multiple episodes to develop effective emission control strategies.