PROBABILITY DENSITY-FUNCTIONS OF PHOTOCHEMICALS OVER A COASTAL AREA OF NORTHERN ITALY

The present paper surveys the findings of experimental studies and ana lyses of statistical probability density functions (PDFs) applied to a ir pollutant concentrations to provide an interpretation of the ground -level distributions of photochemical oxidants in the coastal area of Ravenna (Italy). The atmospheric-pollution data set was collected from the local environmental monitoring network for the period 1978-1989. Results suggest that the statistical distribution of surface ozone, on ce normalised over the solar radiation PDF for the whole measurement p eriod, follows a log-normal law as found for other pollutants. Althoug h the Weibull distribution also offers a good fit of the experimental data, the area's meteorological features seem to favour the former dis tribution once the statistical index estimates have been analysed. Loc al transport phenomena are discussed to explain the data tail trends.