Abstract
To study the influence of emissions and other variables on the urban plume ozone concentration 100 km downwind of the urban boundary in London, UK, factorial experiments were conducted. Nitrogen oxide and VOC emissions from motor vehicles are expected to be a large proportion of the total emission of these species, and the effect of their diurnal variation is apparent in field data. Factorial sensitivity assessments on an expanding box model of the urban plume demonstrate the dominance of urban emissions in the determination of plume maxima 100 km downwind of the urban boundary. NO sub(x) emissions always deplete plume O sub(3) in the short term, while VOC emissions have the opposite effect.