OZONE CASE-STUDIES AT HIGH-ELEVATION IN THE EASTERN UNITED-STATES

A network of five high elevation sites (greater than or similar to> 10 00 m, MSL) in the eastern U.S. measured ozone, NO,, and meteorological parameters as part of the U.S. Environmental Protection Agency's Moun tain Cloud Chemistry Program (MCCP) from May through October in 1986, 1987, and 1988. Analysis of the data showed that high ozone episodes ( greater than or equal to 70 ppbv) at the MCCP sites occurred frequentl y during June and July, and were strongly correlated to synoptic scale meteorological features. A comprehensive statistical analysis was per formed on the data set to investigate the relationship between ozone a nd meteorology. Two major ozone episodes in 1988, each lasting greater than 3 days were examined in detail. The maximum one hour average ozo ne concentration was similar to 160 ppbv recorded at a southern site, Whitetop Mountain, Back trajectory analysis, at 850 mb, indicated that most MCCP sites were influenced by upwind urban and industrial source areas during high ozone episodes. Other meteorological parameters, su ch as temperature, and relative humidity also affect the ozone formati on during the two episodes. The concentrations of NOx were higher duri ng the ozone episodes, reflecting the photochemical production of ozon e in the regional scale.