Master's Thesis Abstract by Stephanie Cooper (1998)

Spatial variation in ozone distribution within topographically complex regions is difficult to quantify because of limitations imposed by the logistics of installing continuous analyzers and collecting data. This study characterized the distribution of ozone in western Washington state, USA, for the Olympic Peninsula and from the north-south urban corridor to the Cascade Mountains (total area = 6,000 km). During summer 1996, we used passive ozone samplers deployed along nine river drainages in conjunction with a sparse network of continuous analyzers to quantify ozone concentrations from near sea level to mountain passes and other high-altitude sites. Weekly average ozone concentrations were higher with increasing distances from the urban core and at higher altitudes, increasing a mean of 1.3 ppbv per 100 meters elevation gain for all mountain transects. Weekly average ozone concentrations were generally highest in drainages east and southeast of the greater Seattle-Tacoma area (maximum = 55 to 67 ppbv) and in the Columbia River Gorge east of Portland, Oregon (maximum = 59 ppbv), and lowest in the western Olympic Peninsula just east of the Pacific Ocean (maximum = 34 ppbv). The presence of higher ozone concentrations in the Columbia River Gorge and Cascade Mountain locations downwind of large cities indicates that ozone and ozone precursors are being transported eastward toward rural wildland areas by prevailing westerly winds. In addition, temporal (week to week) variation in ozone distribution is synchronous within and between all drainages sampled, which indicates that there is regional synchrony in air pollution detectable with weekly averages. These data provide insight on large-scale spatial variation of ozone distribution in complex terrain and can be used to locate areas with greatest ozone exposure. This new ozone database will help regulatory and land management agencies optimize future monitoring networks and identify locations where natural resources and human health could be at risk.