Trace gas concentrations and meteorology in rural Virginia: 1. Ozone and carbon monoxide

Abstract
Carbon monoxide (CO) and ozone (O3) play a central role in the oxidizing capacity of the atmosphere. Standard meteorological parameters and concentrations of these trace gases at Big Meadows, Shenandoah National Park, Virginia, were monitored almost continuously from October 1988 to October 1989. The National Park Service has been measuring O3 at this and two other sites in the park since 1983. Seasonal, monthly, and diurnal variations of hourly averages are examined. In the winter, dry deposition dominates; ozone values are relatively low with CO and O3 negatively correlated. In the summer, photochemistry dominates; ozone values are relatively high, and CO and O3 are positively correlated. Ozone shows a yearly mean mixing ratio of 33 (σ = 12) ppbv and did not exceed the ambient air quality standard during this year. CO mixing ratios averaged 204 (σ = 51) ppbv with no discernible diurnal or seasonal variation. Histograms of hourly means of O3 and CO appear lognormal, but the chi‐square tests for goodness of fit reject the hypotheses. Several lines of evidence suggest that the data are little affected by local sources and are reasonably representative of the regional air quality. The summer of 1989 was cooler than normal, and the average ozone concentration was lower than the 7‐year mean, although an analysis of the full record illustrates no statistically significant trend.

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