NOx or VOC limitation in East German ozone plumes?

The ozone forming potential of VOCs and NOx for plumes observed from severa l cities and a power plant in eastern Germany was investigated. A closed bo x model with a gas phase photochemical reaction mechanism was employed to s imulate several scenarios based upon aircraft observations. In several of t he scenarios, the initial concentrations of NOx, VOCs, and SO2, were reduce d to study the factors limiting the O-3 production. Ozone production was li mited by the initial VOC concentrations for all of the simulated plumes. Hi gher O-3 concentrations were produced with reduced initial NOx. In one samp le with high SO2 mixing ratios (>100 ppb), SO2 was also identified as a sig nificant contributor to the production of O-3.