Ground-Level Ozone Across Kentucky: Modeling and a Synoptic Analysis of High Concentrations
Rural areas are often more susceptible to high concentrations of ground-level ozone (O3) than urban areas. However, rural populations are, for the most part, unaware of this problem. Currently the rural areas of Kentucky have no daily forecast for O3. This research addresses the issue by using methodologies from previous Kentucky O3 modeling research to develop a daily forecast model within Geographic Information Systems. The rural O3 model developed by Kendrick (2005) will be used in this research, as a Standard model, along with an application of the model introduced by Cobourn and Hubbard (1999), as the Hi model, to be used on days that O3 concentrations are expected. When the forecasted maximum temperature is less (greater) than 87°F, the diurnal temperature range is less (greater) than 27, and the probability for precipitation is less (greater) than 50 percent then the Hybrid will choose the Standard (Hi) model. Data for the both models came from the Model Output Statistic by the National Weather Service. The Standard model proves to be successful in forecasting O3 while the Hi model is less accurate. Synoptic meteorology conditions were analyzed to find patterns that are associated with high O3 concentrations for rural areas. Data collected at Mammoth Cave National Park (MCNP) (30 miles north of Bowling Green, KY) during 1998 to 2005 was used in this analysis. The methodology presented by Sheridan (2002) was used to define the overall synoptic patterns that were present during 1998 to 2003. It was found that Dry Moderate and Dry Tropical air masses frequently had high O3 associated with them during late August and early September. The Environmental Protection Agency (EPA) is responsible for policies that fulfill the primary and secondary goals of the National Ambient Air Quality Standards (NAAQS), which includes O3. Prior to 1998 it was determined that al-hour average ambient O3 measurement less than 125 parts per billion (ppb) would be sufficient in achieving both the NAAQS primary and secondary goals. However, it was found that health problems could still occur at levels less than 125 ppb, so the policy was changed to an 8-hour average of 85 ppb. Many researchers explained that this new policy might cause rural areas to break exceedance more often (Baumgardner and Edgerton, 1998; Cobourn and Hubbard, 1999; Barna et al., 2001; Sistla et al., 2001; Reynolds et al, 2003). In this research it was found that the number of exceedance days at MCNP increased by 43 days from the 1-hour to the 8-hour policy. The number of exceedance days has the potential to increase at MCNP if the EPA accepts a proposed 8-hour policy in early 2008. The reason for this proposal is because recently it has been discovered that O3 at levels lower than 85 ppb for 8-hours can affect human health. The proposal requires that the current 8-hour average be adjusted from 85 ppb to a range within 70 - 75 ppb. If accepted the proposed policy would not take effect until 2013.
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