The Sensitivity of Modeled Ozone to the Temporal Distribution of Point, Area, and Mobile Emissions in the Eastern US
The Sensitivity of Modeled Ozone to the Temporal Distribution of Point, Area, and Mobile Emissions in the Eastern US
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Date
2009
Authors
Castellanos, Patricia
Ehrman, Sheryl H.
Stehr, Jeffrey W.
Dickerson, Russell R.
Advisor
Citation
The Sensitivity of Modeled Ozone to the Temporal Distribution of Point, Area, and Mobile Emissions in the Eastern US, P. Castellanos, S. H. Ehrman, R. R. Dickerson, J. W. Stehr, Atmos. Environ., submitted, 2009.
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Abstract
Ozone remains one of the most recalcitrant air pollution problems in the US. Hourly emissions fields
used in air quality models (AQMs) generally show less temporal variability than corresponding
measurements. In order to understand how the daily cycle of estimated emissions affects modeled ozone,
we analyzed the effects of altering all anthropogenic emissions’ temporal distributions by source group
2
on 2002 summer-long simulations of ozone using the Community Multi-Scale Air Quality Model
(CMAQ) v4.5 and the carbon bond IV (CBIV) chemical mechanism with a 12 km grid. We find that
when mobile source emissions were made constant over the course of a day, 8-hour maximum ozone
predictions changed by ±7 parts per billion by volume (ppbv) in urban areas on days when ozone
concentrations greater than 80 ppbv were simulated in the base case. Increasing the temporal variation
of point sources resulted in ozone changes of +6 and –6 ppbv, but only for small areas near sources.
Changing the daily cycle of mobile source emissions produces substantial changes in simulated ozone,
especially in urban areas at night; implications for abatement strategy are discussed.