Atmospheric & Oceanic Science Research Works

Permanent URI for this collectionhttp://hdl.handle.net/1903/1596

Formerly known as the Department of Meteorology.

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End date: 2009Subject: search.filters.subject.ozone

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    Observed Relationship of Ozone air Pollution with Temperature and Emissions
    (American Geophysical Union (AGU), 2009) Bloomer, Bryan J. ; Stehr, Jeffrey W. ; Piety, Charles A.; Salawitch, Ross J.; Dickerson, Russell R.
    Higher temperatures caused by increasing greenhouse gas concentrations are predicted to exacerbate photochemical smog if precursor emissions remain constant. We perform a statistical analysis of 21 years of ozone and temperature observations across the rural eastern U.S. The climate penalty factor is defined as the slope of the ozone/temperature relationship. For two precursor emission regimes, before and after 2002, the climate penalty factor was consistent across the distribution of ozone observations. Prior to 2002, ozone increased by an average of ~3.2 ppbv/°C. After 2002, power plant NOx emissions were reduced by 43%, ozone levels fell ~10%, and the climate penalty factor dropped to ~2.2 ppbv/°C. NOx controls are effective for reducing photochemical smog and might lessen the severity of projected climate change penalties. Air quality models should be evaluated against these observations, and the climate penalty factor metric may be useful for evaluating the response of ozone to climate change.
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    The Sensitivity of Modeled Ozone to the Temporal Distribution of Point, Area, and Mobile Emissions in the Eastern US
    (Elsevier, 2009) Castellanos, Patricia; Ehrman, Sheryl H.; Stehr, Jeffrey W.; Dickerson, Russell R.
    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.